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OF 



ASTRONOMY, 

WITH 

PROBLEMS ON THE GLOBES: 

TO WHICH ARE ADDED 

\ % Glossary of &txm# f 

AND 

QUESTIONS FOR EXAMINATION: 

DESIGNED FOR THE USE OF 

SCHOOLS AND ACADEMIES. 



BY J. TOWLE. 
g 



PHILADELPHIA : 

PUBLISHED BY TOWAR AND HOGAN, 

No. 255, Market street. 

J, H* Cunningham, printer* 

1825- 



I. 



.72 



; 






Southern District of New-YorJc,$$. 

BE IT REMEMBERED, That on the fifteenth day of August, A. D 
1825, in the fiftieth year of the Independence of the United States of 
America, J. Towle, of the said district, hath deposited in this office the 
title of a book, the right whereof he claims as author, in the words fol- 
lowing, to wit : 

" A Grammar of Astronomy, with Problems on the Globes : to which 
are added a Glossary of Terms, and Questions for Examination : designed 
for the use of schools and academies. By J, Toxvle" 

In conformity to the act of congress of the United States, entitled 
" An Act for the encouragement of learning, by securiug the copies of 
Maps, Charts, and Books, to the Authors and Proprietors of such copies, 
during the time therein mentioned." And also to an act, entitled " an 
act supplementary to an act, entitled an act for the encouragement of 
learning, by securing the Copies of Maps, Charts, and Books, to the 
authors and proprietors of such copies, during the times therein men- 
tioned, and extending the benefits thereof to the arts of designing, en- 
graving. a.nd etching historical and other. prints." 

JAMES DILL, 
Clerk of the Smthtm District of Nexo-Yorh 



JAUDON'S EXPOSITOR. 



TOWAR & HOGAN, 

No. 255, Market street, Philadelphia, 

Have lately published a new stereotype edition, on fine 
paper and handsome perspicuous type, of the English 
Orthogiiaphical Expositor : being 1 a Compendious Se- 
lection of the most useful words in the English language, 
alphabetically arranged, divided and explained, accord- 
ing to the most approved modern authorities: also, a list of 
more than eight hundred words, similar, or nearly similar, 
in sound, but of different spelling and import. By Daniel 
Jaudon, Thomas Watson, i*nd Stephen Addington. 

They also have in press, a new edition of the Youth's 
Arithmetical Guide, Improved, with additional Ques- 
tions in Federal Money, &c. by Daniel Jaudon. This 
work will contain all the rules requisite to be taught to 
younger pupils, and especially adapted to Female Acade- 
mies. 

T. & H. have constantly on hand a full supply of School 
Books of every description, whidi they, sell to country 
merchants and teachers on the most Reasonable terms. 






PREFACE- 



On the subjects of Astronomy and the Globes, 
though several valuable but expensive treatises 
are already before the public, the compiler of 
the following pages has experienced no little 
inconvenience for want of a concise work adapted 
to the business of teaching, and to the comprehen- 
sion of beginners. 

The astronomical part of this little treatise is 
intended to prepare the learner to solve the pro- 
blems understandingly. 

] It is unnecessary to burden the reader with 
preliminary observations. The intelligent can 
better judge of the merits of a work by a candid 
perusal, than by all the arguments that can be 
offered in its favour. 

THE AUTHOR. 

New-Yorh 1825. 



COmTBTSTB 



Explanation of Plates . . . . •! .- ? 

History of Astronomy 9 

Solar System . . 12 

Sun 14 

Mercury . . 16 

Yenus 17 

Earth 13 

Mars .21 

Asteroids, or minor Planets .... 22 

Jupiter 24 

Saturn 2G 

Herschel 27 

Tabular view of the Solar System . . . 27 

Secondary Planets . . . . . . 3! 

Moon ........ 31 

Satellites of Jupiter 32 

Satellites of Saturn 33 

Satellites of Herschel ..... 34 

Comets . . . , . . . 34 

Fixed Stars ....... 36 

Constellations . . . . . . 38 

Motion . . . . . . . . 42 

Eclipses . . . ... . . 45 

Table of Eclipses 47 

Tides 48 

Atmosphere 50 

Wind ........ 52 

Table showing the velocity of Winds, &c. . 53 

Climates . . . . . . . 54 

Table showing the breadth of the several cli- 
mates, &c. 54 

Aurora Borealis 56 

Galaxy 57 

Zodiacal light . . . . . . 57 



VI CONTENTS. 

Time 57 

Definitions on the Globes .... 60 

Problems performed by the terrestrial Globe . 65 

Concluding remarks on the terrestrial Globe . 108 

Celestial Globe 113 

Alphabetical list of constellations . . . 115 

Problems performed by the celestial Globe . 118 

Promiscuous exercises on the Globes . . 146 

Glossary of terms 1 50 

Questions for examination . . . 16f> 



EXPLANATION OF PLATES. 



PLATE I. 

A view of the Solar System. 

PLATE II. 

Geometrical Diagrams. 

Pig. 1. Right line. 

2. Curved line. 

3. Parallel right lines. 

4. Parallel curved lines. 

5. An Angle. 

6. A right angle. 

7. An obtuse angle. 

8. An acute angle. 

9. A Triangle. 

10. A Circle. 

A. Diameter. 

B. Radius. 

11. An Ellipsis. 

D. The centre. 

E. One of the foci. 
H. Excentricity. 

12. Comparative magnitudes and distances of the 

primary planets. [See Rev. S. Brown's Ura~ 
nescope.] 

13. Circles of the sphere. 

AB. Ecliptic. 

AC. Tropic of Cancer. 
BD. Tropic of Capricorn. 
EQ. Equator. 

FG. Arctic Circle. 
HO. Horizon. 



Viii EXPLANATION OF PLATES. 

IK. Antarctic circle. 
MN. Meridian. 
PR. Axis. 
P. North pole. 
R. South pole. 

PLATE III. - 

Fig. 1. Laws of motion. . 

2. The apparent retrograde motion ot interior 
planets. 

PLATE nM 

Fr». 1. The umbra and penumbra of a planet's 
shadow. 

2. A total Solar Eclipse. 

3. A total Lunar Eclipse. ] 

4. Diurnal Parallax. 

5. Spring Tides. 

6. Neap Tides. 

7. Positions and phases of the Moon. 

PLATE V. 

Fig. 1. The Seasons. 

2. Vertical and oblique rays. \ 

PLATE VI. 
A Planetarium. 



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Astronomy is a mixed mathematical science, 
which explains the shapes, magnitudes, movements., 
distances, periods, and various phenomena, of the 
celestial luminaries. 

The celestial luminaries are the sun, planets, 
stars, and comets. 



CHAPTER X. 

Of the History of Astronomy, 

1 Astronomy was cultivated, at an early pe- 
riod, by the Chaldeans, Eg}'ptians, Phoenicians, 
Greeks, Arabians, and Chinese. 

2. It was studied, in a particular manner, in 
Chaldea; thence it passed into Egypt; and soon 
after into Phoenicia, where it was applied to the 
uses of navigation, which enabled this people to 
excel others in commerce. 

3. The particular object of their observations, 
was the north polar star. 

4. These observations were at length brought 
into Greece by Thales, who taught the theory of 
the motion of the sun, which accounted for the 
difference in the length of days, the number of 
days in a solar year, the theory of eclipses, and 
the art of foretelling them. 

B 



10 GRAMMAR OF ASTRONOMY. 

5. To Anaximander, the disciple of Thaies, 
Pliny and Diogenes Laertius ascribed the invention 
of the terrestrial globe, or according to Strabo, 
geographical maps. 

6. By these instructions, the Greeks were en- 
abled to make considerable voyages, and to plant 
colonies in different countries. They much im- 
proved their knowledge, by an intercourse with the 
Pythagorean philosophers of Italy, the Druids, and 
the Egyptians; Alexandria being, for a long time, 
the seat of astronomical literature. 

7. The Romans encouraged Astronomy, and 
endeavoured to carry it nearer to a state of per- 
fection. 

8. The x\rabian princes made some exertions to 
promote its cultivation ; and it was at length 
brought to its present state of perfection, by the 
laudable exertions of modern Europeans. 

9. Among the ancient astronomers, Pythagoras 
and Ptolemy were the most noted. Pythagoras 
flourished about 590 years before Christ. In his 
system of the universe, the sun was placed in the 
centre, around which the planets were supposed 
to move. The planets then known, were Mercu- 
ry, Venus, the Earth, Mars, Jupiter, and Saturn. 

10. Ptolemy, the Egyptian astronomer, flou- 
rished 130 years after Christ. He supposed the 
earth to be at rest in the centre, around which 
moved the sun and planets, once a day, in circular 
orbits, in the following order; viz., the Moon, 
Mercury, Venus, the Sun, Jupiter, and Saturn ; 
beyond these were placed the fixed stars. 

11. From that time, Astronomy was much ne- 
glected, until near the close of the 13th century, 
when Alphonsus, king of Castile, formed more ac- 
curate tables than had been before known. 



GRAMMAR OF ASTRONOMY. 21 

12. In the l6th century, this science began to 
assume a rational appearance, by the system of 
Copernicus, which was afterwards perfected by 
Kepler and Galileo. 

13. Nicholas Copernicus, a native of Poland, 
revived the ancient Pythagorean system, A. D, 
1530. His work was published in 1543; a copy 
of which was handed him a few hours before his 
death. 

14. This system met with much opposition ; 
and Galileo was thrown into the prison of the In- 
quisition for supporting it ; nor was he able to re- 
gain his liberty, without first rejecting these opi- 
nions. 

15. These bigots were not Ms only adversaries : 
for even Tycho Brahe, the great Danish astrono- 
mer, was so prejudiced as to reject this discovery. 
From the experiment, that a stone being dropped 
from a lofty tower, fell perpendicularly to its base, 
he inferred that the earth is at rest ; forgetting that 
a stone, being dropped from the top of a ship's 
mast while she is under sail, will fall directly to 
its foot. 

16. Tycho projected another system, in the 
centre of which he placed the Earth, and supposed 
the sun, moon, and stars, to move around it ; after 
which, he made Mercury, Veaus, Mars, Jupiter, 
and Saturn, revolve around the Sun. 

17. These monstrous absurdities died with their 
projector; but we. must still do him the credit to 
say, that his other calculations were far more ac- 
curate than any that preceded them. 

1 S. By the help of Tycho's labours, John Kep- 
ler, a German astronomer, confirmed the true sys*-" 
tern of the universe, and discovered the laws wfei 
regulate motion. 



GRAMMAR OF ASTRONOMY. 

19- Galileo of Florence, is said to have been 
the first who made use of the telescope, and by 
its assistance, discovered many new phenomena; 
as the different phases of Saturn, the satellites of 
Jupiter, their motion, the uneven surface and 
mountains of the moon, the spots of the sun, and 
its revolution about its axis. 

20. We owe much to the labours of the indefati- 
gable Mr. Flamstead, to Dr. Hally, Olbers, Piazzi, 
Harding, and others ; but, perhaps, more to the 
great Sir Isaac Newton and Dr. Herschel, than to 
all their predecessors together. 



CHAPTER IS. 

Of the Solar System. 

1. The system of the celestial bodies, now uni- 
versally received as the true one, is called the So- 
lar, or Copernican System. As we have before 
stated, it was first taught by Pythagoras, 590 years 
before the Christian era ; but it was afterwards re- 
jected, until the sixteenth century, when it was 
revived by Copernicus, from whom it received its 
name. 

2. It comprises the sun, eleven primary, and 
eighteen secondary planets ; besides a number of 
comets. 

3. The primary planets are those which revolve 
around the Sun as a centre ; viz., 1. Mercury £ , 
2. Venus 9 , 3. Earth , 4. Mars g , 5. Vesta ft , 
6. Juno § , 7. Ceres 9 , 8. Pallas £ , 9. Jupiter if, 
10. Saturn £ , 11. Herschel ig. 

4. Four of the primary planets, namely, Vesta, 
Juno, Ceres, and Pallas, are called asteroi 
They are but minor planets. 



GRAMMAR OF ASTRONOMY. 

5* The secondary planets are those which re- 
volve round the primary planets. The earth has 
1, called the moon; Jupiter has 4; Saturn, 7; 
and Herschel, 6. 

6. Comets are wandering bodies, which revolve 
round the sun, in very eccentric orbits ; and are 
only seen when in that part of their orbit nearest 
the sun. * 

7. The Sun is the centre of the system ; around 
which all the primary planets move, in their re- 
spective orbits, from west to east, attended by 
their secondaries or moons. 

8. The orbit of a celestial body, is the line 
which it describes in performing its revolution 
round the sun, or its primary planet. The orbits 
of the planets are elliptical. [See Ellipsis, Glos- 
sary.] 

9. The time which a planet takes to revolve 
round the sun, is called its year; and the time 
which it takes to revolve on its axis, its day. 

10. The axis of a planet, is an imaginary line 
passing through its centre, on which it is supposed 
to revolve. 

11. The sun and all the planets are of a globular 
form, though not perfect globes. 

12. A globe, or sphere, is a body perfectly round , 
having every part of its surface exactly the same 
distance from the centre. 

13. The sun and planets are known to be of a 
globular form, because they bear that appearance 
to the naked eye ; and from the circumstance of 
their casting a circular shadow, during the time of 
an eclipse. 

14. Several things combine to prove that the 
form of the earth is globular. 1. Navigators by 
steering their course directly westward, arrive at 

B 2 



14 GRAMMAR OF ASTRONOMY, 

the same place whence they departed* 2. The 
north polar star becomes more elevated as you 
travel north. 3. The mast of an approaching ship 
is visible before the hull; wh:ch proves the con- 
vexity of the sea. 

15. The Zodiac is that part of the heavens, 
comprising the paths in which the planets move. 
It is divided into 12 equal parts, called signs; viz., 
Aries T» Taurus y , Gemini n? Cancer 55? Leo^, 
Virgo trg, Libra =s=, Scorpio rri, Sagittarius $ , 
Capricornus VC?? Aquarius £?, and Pisces 3£. — 
These are 12 constellations of stars, through which 
the planets appear to pass. 

16. The Ecliptic is the orbit of the earth around 
the sun. All the planets are supposed to cross 
the ecliptic, in two opposite points, called nodes 



CHAPTER XXI. 

Of the Sun, ©. 

1. This grand luminary is a spherical body, si- 
tuated in the centre of the planetary system. Its 
diameter is 883,246 miles. It performs a revolu- 
tion about its axis in 25 days 14 hours 8 minutes; 
and dispenses light and heat to all the planets, in 
proportion to their distances. 

2. The sun is nearer to the earth in the winter 
season, than in the summer. 

3. The sun's diameter forming different angles 
with us, at different times, is a proof that the earth 
moves round the sun, in an elliptical orbit ; and the 
reason that it is notter in summer than in winter, 
is because the sun's rays fall more obliquely on us 
in winter than they do in summer. 

4-. "it is supposed that an atmosphere environs 



GRAMMAR OP ASTRONOMY. 10 

the sun, and that its light and heat are occasioned 
by a gaseous combustion of a phosphoric nature? 
which takes place in the surrounding atmosphere. • 

5. The atmosphere by which the sun is sur- 
rounded, is supposed to extend about 2000 miles 
from its surface; and its density to be at least 
eighty times greater than that which environs the 
earth. 

6. The appearance of the sun's rising in the 
east, and setting in the west, is occasioned by the 
rotation of the earth on its axis. 

7. When the sun is on the meridian of any 
place, it is noon at that place ; and at the opposite 
meridian it is midnight. 

8. The period in which the sun revolves on its 
axis, has been ascertained by means of several 
dark spots viewed through a telescope. In the 
same manner have the rotary periods of Mars, 
Venus, and Jupiter, been ascertained ; hence it is 
supposed that all the planets have the same mo- 
tion, 

Obs. Sir Isaac Newton observes of the sun, 1. That 
its heat is seven times greater in Mercury, than with 
us ; and that water there would be carried off in steam : 
2. That the quantity of matter in the sun, is to that in 
Jupiter, as 1 100 is to 1 : and that the distance of Jupiter 
from the sun, is in the same ratio of the sun's diameter; 
consequently the centre of gravity of the sun and Jupi- 
ter, is nearly in the superficies of the former: 3. That 
the quantity of matter in the sun, is to that in Saturn, as 
2360 to 1 ; and the distance of Saturn from the sun, is in 
a ratio little less than that of the sun's semidiameter ; 
whence the common centre of gravity of Saturn and 
the sun, is a little within the latter: therefore the com- 
mon centre of gravity of all the planets, cannot be more 
than the length of the solar diameter from the centre of 
the sun: 4. The sun's diameter is equal to 100 diame- 
ters of the earth, and the whole bodv exceeds that of the 



' 



[10 GRAMMAR OF ASTRONOMY. 

earth a million of times : 5. If 360 degrees be divided 
by the quantity of the solar year, it gives 59' J", and the 
horary motion" is 2' 27". 



CHAPTER. IV. 

Of Mercury, g . 

1. Mercury is the nearest planet to the sun, 
his mean distance being about 37,000,000 of miles. 
He has a bright bluish appearance. 

2. The diameter of Mercury is 3,224 miles. 

3. His revolution is performed in 87 days 23 
hours ; which is the length of his year. 

4. Mercury revolves on his axis in about 24 
hours, or nearty the same time in which the earth 
revolves : this makes his day about the same length 
as ours. 

5. In his orbit, Mercury crosses the plane of 
the ecliptic in Taurus 15°, and in Scorpio, 15°: 
thus his ascending node is in 15° of Taurus, and 
his descending node in 15° of Scorpio. His great- 
est elongation is 28°. 

6. The velocity of this planet in its orbit, is at 
the mean rate of J 09,500 miles an hour. Its ec- 
centricity is 7,000,000 of miles. 

7. By eccentricity is understood the distance 
between the centre of an ellipsis and either of its 
foci. 

8. When viewed through a good telescope, 
Mercury assumes the different phases, or changes 
of the moon. 

9. When Mercury passes exactly between the 
earth and the sun, lie appears on the sun's disk 
like a small dark spot, or speck. This is called a 



GRAMMAR OF ASTRONOMY. 13 

transit. Only three transits of Mercury have 
been observed. 

10. By the sun's disk, is meant the round face of 
the sun, which, from its distance, appears flat; 



0H4?nsE ir. 

Of Vc?ius, $ . 

1. Venus is the second planet in the system. 
Her situation is immediately within the orbit of 
the earth. Her brilliancy is greater than that of 
any other planet ; and she frequently causes the 
objects on which she shines to cast a shadow. 
Venus may sometimes be seen at noonday. 

2. The d'ameter of Venus is 7,687 miles; and 
her circumference about 24,200 miles. 

3. Her mean distance from the sun is 63,000,000 
of miles; her eccentricity, 473,100 miles; and she 
moves in her orbit at the mean rate of 89,000 
miles an hour. 

4. The annual revolution of Venus is perform- 
ed in about 224 days; and her diurnal rotation, in 
about 23 hours 21 minutes. 

5. Venus, like Mercury, has phases similar to 
those of the moon. 

6. Transits of Venus sometimes happen, though 
but seldom. A transit over the sun's disk, was first 
observed Nov. 16, 1739. 

7. Two transits of Venus will occur in the pre- 
sent century: the former, Dec. 8, 1874, and the 
latter, in 1882. 

8. Venus is sometimes seen as an evening star, 
and sometimes as a morning star. When she is m 
the upper part of her orbit, and rises before fhe 



18 GRAMMAR OF ASTRONOMY. 

sun, she is a morning star ; and when she is in the 
lower part of her orbit, and sets after the sun, an 
evening star. 

9. There have been observed bright and dark 
spots on the disk of Venus : there are also moun- 
tains ; some of which are supposed to be six times 
higher than any on the earth. 

10. The orbit of Venus intersects the plane of 
the ecliptic in 15° of Gemini, and in 15° of Sa- 
gittarius. These are her ascending and descending 
nodes. 

11. She is surrounded with atmosphere, which 
lias been calculated to be 50 miles in height. 



CHAPTER VI. 

Of the Earth, ©. 

1. The Earth, which we inhabit, is the third 
planet from the sun : it is situated between the or- 
bits of Venus and Mars. In shape it is an oblate 
spheroid, elevated at the equator, and depressed at 
the poles. 

2. The mean distance of the earth from the 
sun, is computed to be 95,000,000 of miles. It 
moves in its orbit at the rate of 68,000 miles an 
hour. 

3. The equatorial diameter of the earth, is 7,924 
miles; which exceeds the polar diameter by 37 
miles. The eccentricity of its orbit is 1,618,000 
miles. 

4. The circumference of the earth, measured 
round the equator, is 24,904 miles, and through 
the poles, 24,773 miles. 

5* The earth performs its sidereal revolution 



GRAMMAR OF ASTRONOMY 19 

around the sun in 365 days 6 hours 9 minutes 
12 seconds ; and its tropical, in 365 days 5 hours 
48 minutes 49 seconds ; and revolves on its axis 
in 24 hours. 

6. The sidereal revolution of the earth, is the 
time it occupies in passing from any fixed star, 
till it arrives at the same star again; and its tro- 
pical revolution is the time it takes in travelling 
through the fixed signs of the zodiac ; which is 
the length of the natural year. 

7. In the movement of the earth in its orbit, 
the equinoctial points fall back, in a retrograde 
motion, from east to west, about 50i seconds of 
a degree, or 20 minutes 23 seconds of time every 
year : this retrograde motion is called the reces- 
sion or precession of the equinoxes, 

8. The length of the natural day is 24 hours, 
it being the time which elapses from the sun's ap- 
pearing on any meridian, to the time in which it 
is seen on the same meridian again. 

9. A meridian is a great circle of the sphere, 
which passes through the zenith and poles, per- 
pendicular to the horizon. 

10. The motions of the earth are three ; the an- 
nual, the diurnal, and the recession of the equi- 
noxes. 

11. The inclination of the earth's axis in its 
orbit, produces the variety in the seasons ; namely, 
Spring, Summer, Autumn, and Winter ; and its 
rotation on its axis produces the succession of day 
and night. 

12. The ecliptic makes an angle of 23° 28' with 
a plane passing through the equator of the earth : 
this is called the obliquity of the ecliptic* 

13. As the ecliptic is the apparent path of the 
sun, it will readily be perceived, that his greatest 



JO GRAMMAR OF ASTRONOMY. 

apparent declination from the equator, either north 
or south, can never exceed %3° 28'. 

14. This apparent declination of the sun, is not 
occasioned by his own motion, but by the peculiar 
situation of the earth with respect to the sun. 

15. When the sun is in his greatest apparent 
declination north, the days are longest in a north- 
ern, and shortest in a southern latitude; this hap- 
pens on the 21st of June, at which time the sun 
shines 23° 28 over the north pole. 

16. When the sun is in his greatest apparent 
declination south, the days are longest in a south- 
ern, and shortest in a northern latitude; this hap- 
pens on the 21st of December. The sun then 
shines 23° 28' over the south pole. 

17. The portions of the ecliptic in which the 
earth appears on those days, are called the solsti- 
tial points; these are the first degree of Cancer, 
and the first degree of Capricornus. 

18. At the time of the equinoxes, that is, when 
the sun has no apparent declination, but shines 
equally on both poles, the days and nights are 
equal in length all over the earth. This happens 
twice a year, namely, on the 21st of March, and 
on the 21st of September. 

19. When the earth is in that part of its orbit 
where both the north and the south pole receive 
the sun's rays at the same time, it is said to be in 
its equinox. This happens when the sun appears 
in the constellations of Aries and Libra, the first 
degrees of which are called the equinoctial points. 

20. The declination is greatest at the solstices, 
and nothing in the equinoxes. 

21. The earth is in 1° of Aries, on the 22d 
of September ; 1° of Taurus, on the 24th of Oc- 
+ ober; 1° of Gemini, on the 23d of November: 



GRAMMAR OF ASTRONOMY. 21 

IP of Cancer, on the 21st of December; 1° of 
Leo, on the 21st of January ; 1° of Virgo, on the 
19th of February; 1° of Libra, on the 21st of 
March ; 1° of Scorpio, on the 21st of April ; 1° of 
Sagittarius, on the 21st of May; 1° of Capricor- 
nus, on the 21st of June; 1° of Aquarius, on the 
24th of July ; and 1° of Pisces, on the 24th of Au- 
gust. The sun always appears in the opposite 
signs. 

Obs. The ecliptic being inclined to an angle of 23 ■' 
28' from the equator, the earth, in passing through it, 
must be at different distances from the plane. The near- 
est distance from this plane to the sun's vertical rays, is 
the earWs declination, f commonly called the sun-'s de- 
clination. 

22. To the height of 45 or 50 miles, the earth 
is surrounded by a collection of vapours, called 
atmosphere, which is the support of animal life. 

23. The earth is attended by one secondary 
planet, or satellite, called the moon, which, in the 
sun's absence, dispenses light to the earth, though 
in a less degree than the sun. 



Of Mars, $. 

1. Mars, the fourth planet in order from the 
sun, is of a dusky red appearance, owing proba- 
bly to the density of his atmosphere. Like Mer- 
cury and Venus, he is sometimes in conjunction 
with the sun, but never transits the sun's disk. 

2. When viewed through a telescope, Mars 
sometimes appears full and round ; at other times 
gibbous, but never horned. His apparent motion 

C 



22 URAJYIMAR OF ASTRONOMY. 

is sometimes direct, or from east to west; some- 
times retrograde; and at others, he appears sta- 
tionary. 

3. Mars performs his annual revolution in about 
687 days, at the mean distance of 144,000,000 of 
miles from the sun. The length of his diameter is 
computed to be 4,189 miles, and the eccentricity 
of his orbit, 13,463,000 miles. He moves at the 
mean rate of 55,000 miles an hour. 

4. The diurnal rotation of Mars on his axis, is 
performed in about 24 hours, nearly the same time 
in which the earth performs its rotation. 

5. The orbit of Mars makes an angle of 1° 52' 
with the plane of the ecliptic. The place of his 
ascending node is in 18° of Taurus. 

6. When Mars rises before the sun, he is seen in 
the morning ; but when he sets after the sun, he is 
seen in the evening. 

7. It is evident that the orbit of Mars is without 
that of the earth, as he is sometimes seen opposite 
to the meridian at noonday. 

8. The earth would appear to the inhabitants of 
Mars, as Venus appears to us. 



OHAPfEE VIIE. 

Of the four Asteroids, or Minor Planets. 

1. Vesta, one of the minor planets, was disco- 
vered by Dr. Gibers, of Bremen, in Lower Saxo- 
ny, March 29, 1807. It is visible to the naked 
eye, only in very clear evenings. It shines with a 
pure white light, and appears like a star of the 
fifth magnitude. 



GRAMMAR OF ASTRONOMY* 23 

2. The diameter of Vesta is computed to be 
238 miles ; and its mean distance from the sun, 
225,000,000 of miles. It revolves round the sun 
in about 3 years 60 davs, at the mean rate of 
44,201 miles an hour. The eccentricity of its 
orbit is 30,000,000 of miles ; but the time which 
it takes to perform a revolution on its axis, is not 
known. 

3. Juno was discovered by Mr. Harding, near 
Bremen, on the 1st of September, 1804. It is 
situated between the orbits of Vesta and Pallas, 
and shines with a brilliant light, owing probably 
to certain changes in the density of its atmo- 
sphere. 

4. The diameter of Juno is computed, to be 
1,425 miles; and its mean distance from the sun, 
252,000,000 of miles. It performs its annual re- 
volution in 4 years 128 days, at the rate of 41,170 
miles an hour. Its eccentricity is 68,000,000 of 
miles. 

5. Ceres, the next planet to Juno, was disco- 
vered by M. Piazzi of Palermo, in the island of Si- 
cily, January 1, 1801. It exhibits a ruddy appear- 
ance, owing to the dense atmosphere by which it 
is surrounded ; and, to the naked eye, its size is 
that of a star of the sixth magnitude. 

6. The diameter of Ceres is 1,024 miles; and 
its mean distance from the sun is about 263,000,000 
of miles. It revolves around the sun in 1,681 days 
12 hours 9 minutes, or about 4 years 221 days, at 
the mean rate of 40,930 miles an hour. The ec- 
centricity of its orbit is computed to be 20,598,130 
miles. 

7. The height of its atmosphere, according to 
Shroeter, the German astronomer, is 676 miles. 

8. Pallas was discovered bv Dr. Olbers of Bre- 



24 GRAMMAR OF ASTRONOMY. 

men, March 28, 1802. Its appearance is not so 
ruddy as that of Ceres, by reason of the less ex- 
tent of its atmosphere, which is computed to be 
468 miles in height. 

9. Shroeter estimates the diameter of Pallas 
at 2,099 miles ; and its distance from the sun, 
265,000,000 of miles. 

10. It performs its revolution round the sun in 
1,703 days, at the rate of 40,930 miles an hour ; 
and its eccentricity is about 64,516,673 miles. 

11. The orbit of Pallas crosses that of Ceres, 
in consequence of the great eccentricity of the 
former. 

Obs. As the great space between the orbits of Mars 
and Jupiter, does not, without another planet, seem to 
agree with the harmony of proportionable distance in 
the solar system, the four minor planets are supposed, 
by some astronomers, to have been separated from one 
original planet, by some convulsion in nature, capable 
of destroying the mutual attraction of the fragments. 
It is evident that the smaller parts would, by the explo- 
sive force, be thrown to the greatest distance from the 
original orbit, while vthe greater fragments, on account 
of their gravity, deviate less from the original path of 
the primary body. Thus Pallas and Juno are supposed 
by some to be less than Ceres and Vesta, because of 
their greater eccentricity. 



CHAPTER IX. 
Of Jupiter, 11 . 

1. Jupiter, the next planet in order, and the 
largest in the solar system, is situated between the 
orbits of Pallas and Saturn. 

% The diameter of Jupiter is about 89,170 



GRAMMAR OF ASTR0N0MV. 25 

miles ; and his mean distance from the sun, about 
490,000,000 of miles. 

3. Jupiter performs his annual revolution around 
the sun in 4,330 days 14 hours 19 minutes, or 
about 19 years 10| months, at the mean rate of 
298,660 miles an hour. 

4. Jupiter revolves on his axis in 9 hours 55 
minutes 39 seconds, consequently his night can 
never be 5 hours in length. 

5. As the axis of this planet has no inclination; 
there is no change in its seasons. 

6. In the polar regions of Jupiter, there is per- 
petual winter ; and about the equator, perpetual 
summer. 

7. The appearance of Jupiter is bright, but, by 
reason of his greater distance, is less so than Ve- 
nus. 

8. When Jupiter is seen west of the sun, he 
has the appearance of a morning star ; but when 
seen east of the sun, he has the appearance of an 
evening star. 

9. In his orbit, Jupiter forms an angle of 1° 20' 
with the plane of the ecliptic. 

10. The sun appears five times larger to us ? 
than it does to the inhabitants of Jupiter ; conse- 
quently their light and heat are less in proportion. 

11. Jupiter appears to be surrounded with belts, 
which are supposed to be clouds floating in his at- 
mosphere. These belts are always parallel to his 
equator, and are interspersed with dark spots, 
which are supposed to be clouds more dense than 
the others. By observing these spots through a 
telescope, the time of Jupiter's rotation on his 
axis has been ascertained. 

12. This planet is constantly attended by 4 

C 2 



26 GRAMMAR OF ASTRONOMY. 

satellites, or moons, which revolve about it, and 
compensate, in part, for the want of light, occa- 
sioned bv its remoteness from the sun. 



CHAPTER X. 

Of Saturn, ^ . 

1. Saturn is situated between the orbits of Ju- 
piter and Herschel, and revolves around the sun, 
from which his mean distance is 960,000,000 of 
miles. 

2. The diameter of Saturn is 79,042 miles ; 
and his circumference, about 244,137 miles. 

3. Saturn performs his annual revolution around 
the sun, in 10,746 da} r s 19 hours 16 minutes, or 
about 29 years and a half; and moves at the mean 
rate of about 22,000 miles an hour. 

4. The orbit of Saturn forms an angle of 2° 30 f 
with the plane of the ecliptic. His eccentricity 
is estimated at 49,000,000 of miles. His ascend- 
ing node is 22° of Cancer ; and his descending 
node, 22° of Capricornus. 

5. This planet performs a daily revolution on its 
axis in 10 hours 16 minutes 2 seconds. 

6. To the naked eye, it appears like a star of 
the second magnitude. In consequence of its 
great distance from the sun, the light which it re- 
flects, is less than that of Jupiter. 

7. When viewed through a good telescope, Sa- 
turn exhibits a beautiful appearance, being deco- 
rated with various belts, interspersed with spots, 
and encompassed by a bright luminous double 
ring, which very much resembles the wooden hori- 
zon of an artificial globe. 



GRAMMAR OF ASTRONOMY. T( 

8. The ring has a motion on its axis, and casts 
a shadow on the surface of the planet, which leads 
some to suppose that it is solid. It was discovered 
in 1609, by Galileo. It revolves about Saturn in 
10 hours 33 minutes. 

9. The distance between Saturn and his inner 
ring, is 21,000 miles ; and between the inner and 
the outer ring, 2,839 miles. The inner ring being 
2,000 miles in breadth, and the outer, 7?200 miles, 
the whole distance from the surface of Saturn to 
his outward boundary, is 51,039 miles. 

10. The belts, or zones of Saturn, are similar 
to those of Jupiter, and their appearance may be 
attributed to the same causes, namely, to clouds 
floating in their respective atmospheres. 

11. There have been various conjectures con- 
cerning the substance of Saturn's ring. Some 
have supposed it to be composed of a vast 
assemblage of planets ; others have supposed it 
to be a permanent bright cloud. — Whatever may 
l?e its substance, it undoubtedly reflects the light 
of the sun on the planet. 

12. Saturn has 7 moons, or satellites, which 
constantly attend him in his grand revolution around 
the sun. Five of these satellites were discover- 
ed by Cassini and Huygens ; and the other two, 
by the celebrated Dr. Herschel, with his telescope, 
which magnified not less than 6,000 times. 



CBAPISft XI. 

Of Herschel, J£. 

1. Herschel, the last planet in the solar system, 
and most distant from the sun. was discovered by 



28 GRAMMAR OP ASTRONOMY. 

Dr. Herschel, at Bath, in England, March 13, 
1781. It shines with a bluish white light, and is 
seldom seen without the aid of a telescope of great 
magnifying power. 

2. The diameter of this planet is 35,112 
miles; and its mean distance from the sun, about 
1,800,000,000 of miles. 

3. It performs its annual revolution around the 
sun in 30,637 days 4 hours, or 84 years 2 months 
and a half. The time which it occupies in per- 
forming a revolution on its axis, has not yet been 
determined. In its orbit, it moves at the mean 
rate of about 15,546 miles an hour. 

4. The orbit of Herschel is nearly parallel with 
the plane of the ecliptic, forming an angle of 
only 46'. His eccentricity is 84,800,000 miles. 
His ascending node is 12° of Gemini ; and his de- 
scending node 12° of Sagittarius. 

Obs. The name given to this planet, by its discover- 
er, was Georgium Sidus:. others on the continent have 
called it Uranus, as Mars was the son of Jupiter, so Ju- 
piter was the son of Saturn, the father of whom, among* 
the heathen deities, was called Uranus : others h?,ve, 
with more propriety, given it the name of Herschel, in 
honour of its discoverer, which name we have preferred. 

5. A planet may easily be distinguished from a 
fixed star ; for the former shines with a steady- 
light, but the latter is constantly twinkling. 

6. Herschel is constantly attended by six satel- 
lites, or moons, the orbits of which are nearly per- 
pendicular to that of their primary. 

7. The light and heat which Herschel derives 
from the sun, is 360 times less than what is derived 
by the earth. 



GRAMMAR OF ASTRONOMY 



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GRAMMAR OF ASTRONOMY. 

CHAFVBR XIX, 

Of the Secondary Planets, 

1. A secondary planet revolves around a pri- 
mary one as a centre, in the same manner as its 
primary revolves around the sun. 

2. Though a secondary planet gravitates princi- 
pally towards its primary as a centre, yet its mo- 
tion is much influenced by the attraction of the 
sun ; consequently, the movement in its orbit is 
not so uniform as that of its primary. 

Of the Moon. 

3. The Moon is a satellite to the earth, and par- 
tially supplies it with light, in the absence of the 
sun. It is an opaque body, in shape nearly globu- 
lar, and in size about one fifth part of the earth. 
Its diameter is 2,180 miles ; and its circumference, 
about 6,851 miles. 

4. The mean distance of the moon from the 
earth, is 240,000 miles ; and from the sun, 
95,000,000 of miles. It moves in its orbit around 
the earth, at the rate of 2,290 miles an hour. 

5. The moon performs a rotation on its axis, in 
27 days 7 hours 43 minutes 5 seconds, which is 
the length of its lunar day : this is also the length 
of the lunar month. 

6. By the phases of the moon, are meant the 
changes observable in its shape : it is sometimes 
full ; sometimes horned ; and at others, gibbous, 
according to the situation of the dark side with 
respect to the earth. 

7. Neio moon is when the moon is in conjunc- 



32 • GKAStolAR OF ASTRONOMY. 

tion, i e. when it is between the earth and the 
sun, the dark side being presented to us. 

8. Full moon is when it is in opposition, i. e 
when the earth is between the sun and the moon' 
and the illuminated side is presented to us. 

Of the Satellites of Jupiter. 

9. To make up for the deficiency of light c 
casioned by the great distance of Jupiter from the 
sun, he has 4 satellites, or moons, which revolve 
around him, from west to east, at different periods 
in 1610 CS * y W6re discovered °y Galileo 

10. The first satellite is 252,511 miles distant 
Irom the centre of Jupiter, and revolves around 
him ml day 18 hours 27 minutes 33 seconds 

Jtt Th ^ second 1 ,s 40 ° 5 810 miles distant, and 
performs its revolution in 3 days 13 hours T» 
minutes 42 seconds. y UrS lo 

12. The third is 640,406 miles distant, and per- 
SSf° 1U,,OD m 7 '^ 3 h0Urs « minute. 

13. The fourth satellite of J U pi ter j s t 126 79 , 
miles distant, and performs its revolution in 16 
days 16 hours 32 minutes 8 seconds 

14. The satellites of Jupiter are of the great 
est importance ,„ finding the longitude of p£S 
by observing their immersion and emersion as 
these take place at the same instant of time foe ve! 

? ¥ T °J tJ ? e ea i th - The first satellite fa consi 
dered the best for this purpose, as t is better 
known than the others, and its eclioses hannen 
more frequently. «-"pses Happen 

15. The immersion and emersion of Jupiter's 
satellite* are found in the Nautical AlmanT/ac- 



GRAMMAR OF ASTRONOMY. So 

eurately calculated for the meridian of Green- 
wich. 

16. The angles of the orbits of Jupiter's moons, 
as seen from the earth, are as follow : the first is 
3' 55" ; the second, 6' 14" ; the third, 9' 58"; and 
the fourth, 17' 30". 

Of the Satellites of Saturn. 

17. In addition to his luminous ring, Saturn has 
7 satellites. 

18. The first satellite is 111,534 miles distant 
from Saturn, and revolves around him in 22 hours 
37 minutes 23 seconds. 

19. The second is 139,904 miles distant, and 
performs its revolution in 1 day 8 hours 53 mi- 
nutes 9 seconds. 

20. The third is at the distance of 172,222 
miles, and performs its revolution in 1 day 21 
hours 18 minutes 27 seconds. 

21. The fourth is at the mean distance of 
216,507 miles, and performs its revolution in 2 
days 17 hours 44 minutes 51 seconds. 

22. The fifth performs its revolution in 4 days 
12 hours 25 minutes 11 seconds, at the mean dis- 
tance of 314,920 miles. 

23. The mean distance of the sixth, is 708,570 
miles, and it performs its revolution in 15 days 
22 hours 41 minutes 16 seconds. 

24. The seventh satellite of Saturn performs its 
revolution in 79 days 7 hours 53 minutes 43 se- 
conds, at the mean distance of 2,125,910 miles. 
This last satellite of Saturn has been observed to 
perform a rotation on its axis, like the moon. 



D 



34 GRAMMAR OF ASTRONOMY. 

Of the Satellites of Herschel. 

25. Herschel has 6 satellites, all of which were 
discovered by Dr. Herschel. 

26. The first performs its revolution around its 
primary in 5 days 21 hours 25 minutes,. at the dis- 
tance of about 204,000 miles. 

27. The second planet is about 290,000 miles 
distant, and performs its periodical revolution 
in 8 days 17 hours 1 minute 19 seconds. It was 
discovered Jan. 11, 1787- 

28. The third performs its revolution in 10 days 
23 hours 4 minutes. Discovered March 26, 1794. 

29- The fourth is about 388,000 miles distant, 
and performs the period of its revolution in 13 
davs 11 hours 5 minutes. Discovered January 11, 
1787. 

~ 30. The fifth completes its revolution in 38 
days 1 hour 49 minutes, at the distance of about 
777,000 miles. Discovered February 9, 1790. 

31. The revolution of the sixth is completed in 
107 days 16 hours 40 minutes, at the distance of 
about 1,500,000 miles. 

32. The orbits of Herschel's satellites are said 
to be nearly perpendicular to the plane of the 
ecliptic, and to perform their revolutions in a re- 
trograde motion, contrary to the older of the signs* 



Of Comets. 

1 . Comets are certain wandering bodies, belong- 
ing to the solar system, which move round the sun, 



GRAMMAR OF ASTRONOMY. 35 

in very eccentric orbits. They have no visible 
disk, and shine with a faint nebulous light, accom- 
panied with a train or bright streak, in a direction 
opposite the sun. 

2. In some parts of their orbits, they approach 
very near the sun ; and thence disappear in nfi- 
nite space, receding beyond the confines of Her- 
scheL 

3. Comets appear in every region of the hea- 
vens, and move in every possible direction, some- 
times travelling directly in the order of the zodiacal 
signs, and at others in a retrograde motion. 

4. The ancients believed that comets were 
ominous of plagues, wars, famines, &c. ; and were 
sent by the Deity to punish mankind for their 
crimes. 

5. From the numerous observations made on 
the comet of 1680, Sir Isaac Newton concluded 
that, agreeably to his theory, comets revolve about 
the sun, but in very eccentric ellipses. 

6. The movement of comets is much accelerat- 
ed when moving towards the sun, and retarded 
when moving from it. 

7. The comet of 16S0, approached within about 
130,000 miles of the sun ; and, at its perihelium, 
was supposed to move at the rate of 880,000 miles 
an hour. 

8. Comets 'appear to be much affected in their 
orbits, by the attractive action of the primary pla- 
nets. 

9. About 500 comets have been observed by the 
ancient and modern astronomers ; but the elements 
of only 97 have been ascertained. 

10. From observation, it appears that 24 comets 
have passed between the orbit of Mercury and the 
sun ; 33 between the orbits of Mercury and Ve- 



oO GRAMMAR OF ASTRONOMY. 

nus ; 21 between the orbits N of Venus and the 
earth; 15 between the orbits of the earth and 
Mars ; 3 between the orbits of Mars and Ceres ; 
and 1 between the orbits of Ceres and Jupiter. 

11. Comets are of various magnitudes, but the 
greater number of them are supposed to be less 
than the moon. 

12. Various conjectures have been entertained, 
respecting the bright lucid train extending from 
the nucleus of comets. It is most probably a thin 
vapour ignited by means of the sun's heat : comets 
must consequently be surrounded with atmo- 
sphere. 

13. The system of comets is still somewhat in 
obscurity ; but we must depend upon the opinions 
of Newton, Hally, Euler, Clairant, Kepler, and 
Sexell, until multiplied observations shall have 
added to the imperfect knowledge which we at 
present possess, respecting those singular bodies. 



Of the Fixed Stars. 

1. Fixed stars are luminous bodies appearing 
stationary in the heavens, at the same distance 
from each other. They are supposed to be of the 
same substance and properties as the sun ; or to 
be suns to other systems. They are at such im- 
mense distances from us, as to appear like small 
twinkling dots, or points. 

2. The fixed stars appear to shine by their own 
effulgence, with an unsteady, twinkling light ; 
whereas the light of the planets is steady, always 
having the same appearance- 



GRAMMAR OF ASTRONOMY. 37 

3. The fixed stars appear to have a motion on 
their axes like the sun; and as the earth revolves 
from west to east, they appear to move from east 
to west. 

4. As the north pole of the earth always points 
directly to the polar star, that star appears immova- 
ble ; and its elevation above the horizon of any 
place, is always equal to rhe latitude of the place. 

5. Not more than a thousand stars, above the 
horizon, are at once visible to the naked e} r e ; and 
the appearance of so innumerable a multitude, as 
are observable on a clear winter's evening, is 
owing to the incessant twinkling, occasioned by a 
division of the particles of light escaping through 
the mists of the atmosphere. 

6. The fixed stars, being at so great a distance, 
are not increased in size when viewed through 
glasses of the greatest magnifying power. 

7. In order to ascertain the situations of these 
stars the more readily, they have been divided in- 
to constellations ; and to distinguish their relative 
sizes, they have been classed into six magnitudes ; 
namely, the largest are called stars of the first 
magnitude ; those next in size, stars of the second 
magnitude; and so on to the sixth or last magni- 
tude. 

Ob 1% must not be inferred that all the stars of each 
class appear of exactly the same magnitude, there be- 
ing great latitude given in this respect; even those of 
the first magnitude appear almost all different in size 
and lustre. There are also' other stars of intermediate 
magnitudes, which, as astronomers cannot refer them 
to any one particular class, they place between two 
classes. Proc}^on, for instance, which Ptolemy makes 
of the first magnitude, and Tycho of the second, Flam- 
stead lays down as between the first and the second. 
Wherefore, instead of six magnitudes, we may say that 

j) 2 



S8 



GRAMMAR OF ASTRONOMY 



there are almost as many as there are stars, such con- 
siderable varieties being observable in their magnitude, 
colour, and brightness. 

8. Those stars which are not arranged under 
any constellation, are called unformed stars ; and 
those which appear for a season, are called peri- 
odical stars. 



CHA^TISB, XV. 

Of the Constellations. 

i. A constellation is a cluster of stars forming 
a groupe, which astronomers have supposed to re- 
semble the outlines of some animal ; for the con- 
venience of distinguishing them. 

2. Stars are classed into 91 constellations or 
groupes ? namely ; 12 in the zodiac, 34 in the 
northern hemisphere, and 45 in the southern. 



I. CONSTELLATIONS IN THE ZODIAC. 




Num- 


]S times of the principal 
Stars and their Mag- 


CONSTELLATIONS. 


ber of 




Stars. 


nitudes. 


1. Aries, The Ram, 


66 


Arietis, 2. 

C Aldebaran, 1. 


2. Taurus, The Bully 


141 


< The Pleiades. 
CThe Hyades. 


3. Gemini, The Twins, . 


85 


( Castor and Pollux. 
( 1. 2. 


4. Cancer, The Crab, 


83 




5. Leo, The Lion, . 


95 


5 "Regulus, or Lion's. 
1 Heart, I. 


6. Virgo, The Virgin, 


110 


\ Spica Virginis, 1 
I Vindemiatrix, 2. 


7. Libra, The Balance, . 


51 




8. Scorpio, The Scorpion, 


44 


Antares, 1. 


9. Sagittarius, The Archer, 


69 




10. Capricornus, The Goal, 


51 




11. Aquarius, The Water-bearer, 


108 


Scheat, 3: 


12. Pisces, The Fishes, 


113 





GRAMMAR OF ASTRONOMY. 



30 



II. THE NORTHERN CONSTELLATIONS. 



CONSTELLATIONS. 



Num- Names of the principal 
her of Stars, and their Mag 
Stars. I nitudes. 



10 

11. 

12. 

13. 

14. 
15. 

16 
17. 
18 

19. 

20. 
21. 

22. 



Mons Maenalus, The Mountair 
Ma&nalus, 

Serpens, The Serpent, 
Serpentarius, The Serpent-bear- 
er, .... 
*Taurus Poniatowski, Bull of 
Poniatowski, 

* Scutum Sobieski, Sobieskis 
Shield, . . . . 
( Aquila, The Eagle, ) 
( Antinous, ) 

Equulus, The little Horse, . 
Leo Minor, The little Lion, 
Coma Berenices, Berenices 
hair, . . 

C Asterion et Chara, vel, ^ 

< Canes Venatici, The Gray- > 
C hounds, . . ) 

Bootes, .... 

Corona Borealis, TJienorthern 
Crown, .... 
C Hercules, . . p 

< Cerberus, The three-headed > 
C Dog, . . ) 
Lyra, The Harp, . - . 
Vulpecula et Anser, The Fox 
and Goose, 

Sagitta, The Arrow, 
Delphinus, The Dolphin, . 
Pegasus, The Flying Horse, 

Andromeda, 

Triangulum, The Triangle, 
Triangulum Minus, The Little 
Triangle, 
*Musea, The Fly, . 



11 

64 

74 

7 

8 
71 

10 

53 

43 
25 

54 

21 

113 

21 

35 
18 
18 

89 

66 

n 

5 
6 



Ras Alhasrus, 2. 



Altair, 1. 



Deneb, 2. 



( Arcturus, 1. Mi- 
( rach, 3. 

Alphacca, 2. 
C Ras Algethi 3 in 
< the head of Her- 
C cules. 
Vega, 1. 



Markab,2. Scheat,S 
JMirach, 2. Al- 
( maach, 2. 



40 



GRAMMAR OF ASTRONOMY, 



NORTHERN CONSTELLATIONS. 


The following northern constellations 


Num- 


Names of the primcif a 


do not $vt in the latitude of Lon- 


ber oj 


Stars, and tk>: i> M-r. - 


don. 


Stars 


nitudes. 


23. Ursa Minor, The Little Bear, 


24 


Pt.le Star, 2. 
C Dubhe, 2. Aii- 
< oih, 2. Benet- 
C nach, 2. 


24. Ursa Major, The Great Bear, 


87 






25. *Cor Carol i, Charles's Heart, 


3 




26. Draco, The Dragon, 


80 


Rastaben, 2 


27. Cygnus, The Swan, . 


81 


D eb Adige, 1. 


28. Lacerta, The Lizard, 


16 




29. Ccpheus. .... 


35 


Alderamin, 3. 


30. Casiope, .... 


55 


Schedai , 3. 


C Perseus. . . ~) 

31. < Caput Medusae, The Head £ 

C of Medusa, . . j 


59 


S Algenib, 2. 
} Algol, % 


32. Cameleopardalus, The Ca- 






meleopard, 


58 




33 Auriga, The Charioteer or 






Wagoner, 


66 


Capella, 1 


34. Lvnx, The Lynx, 


44 




III. THE SOUTHERN C 


ON ST 


ELLATIONS. 




A'ZLD.- 


.Vermes oj the principal 


CONSTELLATIONS. 


her of 


Stars, and thti. Mag- 




Si , s. 


nitudes. 


1. Celus, The Whale, . 


97 


Menkar, 2 


2. Eridanus, The river Po, . 


84 


^rcherner, 1 
CBellatrix,2. Be- 


3. Orion, .... 


78 


*\ telgues, 1. Ri- 
C gel, 1 


4. Monoceros, The Unicorn, . 


31 




5. Canis Minor, The little Dog, 


14 


Procyon, 1. 


6. Hydra, .... 


60 


Cor Hydrae, 1. 


7. Sexians, The Sextant, 


41 




<j *Microscopium, The Micros- 






scope, .... 


10 




9- Piscis Nodus vel Australis, 






The southern Fish, . 


24 


Fomalhaut, 1 


10. * Officina Sculptoria, The 






Sculptor's Short, 


12 





GRAMMAR OF ASTRONOMY. 






SOUTHERN CONSTELLATIONS. 


Num- 
ber of 
Stars 


Names of the princi- 
pal Stars, and their 
Magnitudes. 


21. *Fornax Chymica, The Furnace, 
12 Brand^nburgiumScepirum, The 
Sceptre of Brandenburgh, 

13. Lepus, The Hare-, 

14. *Columba Noachi, Noah's Dove. 

15 Canis Major, The great Dog, 

16 *Pyxis Nautica, The Mariner's 

Compass, . . 
17. *Maohiaa Pneumatiea, The Air 
Pump, .... 

18 Crater, The Cup or Goblet, . 

19 Corvus, The Crow, 


14 

3 
19 
10 
31 

4 

3 
31 

9 


Sirius, 1. 

- 

Alkes, 3. 
Algorab, 3. 


The following southern constellations do 
not rise in the latitude of London. 


Num- 
ber of 

Stars. 


Names of the princl- 
pal Stars, and theb 
Magnitudes . 


20. Centaurus, The Centaur, 

21. Lupus, The Wolf, 

22. *Norma, vel Quadra Euclidis, 

Euclid'' s Square, 

23. *Circinus, The Compasses, 

24. ^Triangulum Australe, The 
southern Triangle, 

25. *Crux, The Cross, 

2o* *Mu^ca Austral is, vel Apis, The 

southern Fly, or Bee, 
27- *Chamseleon, The Chumeleon, 
28. Ara, The Mar, . 

29 Telescopium, The Telescope, 

30 Corona Austral is, The southern 

Or own, 

31 *Indus, The Indian, 

32 "^Grus, he Crane, 

33. *Pavo, The Peacock, . 

34. *Aous, ve! Avis Indica, The 

Bird, of Paradise, 

35. *Octans Hadleianus, Hadleifs 

Octant, .... 

36. *Phoe:iix, .... 

37. *Horologium, The Clock, 

38. *Reticulus Rhomboidalis, The 
Rhojnboidal Net* . 

39. Hydrus, The Water-snake, ► 

40. Toucan, The American Goose, 


35 

24 

12 

4 

5 
.5 

10 

9 
9 

12 

12 
13 
14 

11 

43 
13 
12 

10 

10 

9 





42 



GRAMMAR OF ASTRONOMY. 



SOUTHERN CONSTELLATIONS. 


The following southern constellations do 




- of tht prh - 

Stars, (i^d tht • 


not rise in the latitude of London. 


Magnitudes 


41. Mons Mensae, The Table Moun- 






tain, . . 


30 




42. * Praxiteles, vel Cela Sculpturia, 






The graver s or engraver's Tools, 


16 




43. *EquuleusPictoreus, The Paint- 






er's Easel, 


8 




44. *Dorado, or Xiphias, The Sword 






Fish, . 


6 




45. Argo Navis, The ship Argo, . 


64 


Canopus, 1 


46. * Pise is Volans, The Flijing Fish, 


8 




47. *Robur Caroli, Charles s Oak, 


12 





CHAPTER. XVZ. 
Of Motion. 

t. Motion is defined to be a continued and suc- 
cessive change of place. We are principally ac- 
quainted with two kinds of motions in the beings 
that surround us : one is that by which an entire 
body is transferred from one place to another, as 
the falling of a stone or the sailing of a ship ; the 
other is a motion of parts of bodies among them- 
selves, as the growth of animals and plants, the 
expansion or contraction of bodies, their composi- 
tion and decomposition. 

2. Heat causes the expansion, and cold the con- 
traction of bodies ; and, as the temperature is al- 
ways varying, the particles of the mpst solid bo- 
dies are continually changing place. 

3. In the consideration of motion, several things 
must be attended to, nam el v : 



GRAMMAR OF ASTRONOMY. 43 

1. The force which impresses the motion ; 

2. The quantity of matter in the moving body \ 

3. The velocity of the motion ; 

4. The space passed over ; 

5. The time occupied in passing ; and 

6. The force with which it strikes an opposing 
body. 

4. In a mechanical sense, every body, by its 
inertness, resists all change of place, and conse- 
quently remains in a state of rest, until impelled 
by some moving force ; as the action of men and 
other animals, wind, water, gravity, the pressure 
of the atmosphere, and the elasticity of fluids and 
other bodies. 

5. A body, when once put in motion, will for 
ever continue to move uniformly, unless resisted 
by some opposing power. Velocity of motion is 
.estimated by the time employed in passing over a 

certain space, or by the space moved over in a 
certain time. 

, 6. A body in motion must always tend to some 
particular point, in which case the motion will be 
in a straight line ; or it may continually change 
the point of its direction, which will produce a 
curvilinear direction. 

7. The motion of a body will be in the same 
direction in which the moving force acts. 

8. If several powers differently applied or di- 
rected, act upon it at the same time, as it cannot 
obey them all, it will obey no one of them, but 
move in a direction somewhat between them : 
this is what is called the composition and resolu- 
tion of motion. 

9. Whenever we see a body moving in a cur- 
vilinear direction, we may be certain that it is 
acted upon by tivo forces at least ; and when one 



44 GRAMMAR OF ASTRONOMY. 

of these two forces ceases to act, the body will 
again move in a straight line : thus a stone in a 
sling is moved round by the hand, while it is pull- 
ed towards the centre of the circle which it de- 
scribes by the string ; but when the string is let. 
go, the stone flies off in a tangent to the circle. 

10. Every body moving in a circle, has a tenden- 
cy to fly off from its centre, which tendency is 
called the centrifugal force : — this is opposed to 
the centripetal force, or that which, by drawing 
bodies towards the centre, makes them revolve in a 
curve. These two forces are together called cen- 
tral forces. 

11. The centre of gravity of a body, is that 
point about which all the parts of a body do, in 
any situation, balance each other. Hence if a 
body be supported by this point, it will rest in any 
position in which it may be placed. 

12. Whatever supports the centre of gravity of 
any body, bears the weight of the whole body ; 
and while this is supported, it cannot fall. — We 
may therefore consider the whole weight of any 
body as centred in this point. 

13. The common centre of gravity of any two 
or more bodies, is the point about which they 
would equiponderate or rest in any position. 

14. Motion, in astronomy, may be divided into 
real and apparent. Real motion is the actual 
movement of any body ; as the revolution of the 
earth Apparent motion is when a body appears 
to move, when it is actually at rest ; as the appa- 
rent motion of the sun and stars, produced by the 
real motion of the earth. 



GRAMMAR OF ASTRONOMY 45 

OEAFTIE KITH, 
Of Eclipses. 

1. An eclipse is an obstruction of the sun's ray*, 
caused by the interposition of the dark body of a 
planet. 

2. Every planet, being illuminated by the sun, 
casts a shadow in a direction opposite to the sun ; 
consequently a planet passing through this shadow, 
is darkened by it, the sun's rays being obscured 
by the intervening planet. 

3. There are commonly considered two kinds 
of eclipses, namely, that of the sun, and that of a 
planet. 

4. An eclipse of the sun is the obscuration of 
his light, occasioned by the interposition of the 
moon between the earth and the rays of the sun. 
or by the earth's passing through the shadow of 
the moon, she being near one of her nodes. 

5. Eclipses of the sun happen only when the 
moon is in conjunction with the sun ? as at the time 
of new moon. 

6. A partial eclipse of the sun is when the pe- 
numbra or imperfect shadow of the moon, falls 
upon that part of the earth's surface where the 
partial eclipse is seen. 

7. A total eclipse of the sun is when the moon's 
shadow falls upon that part of the earth where 
the eclipse is observed. 

8. An eclipse of the sun will be central at new 
moon, when she is in one of her nodes. 

9. An annular eclipse of the sun is when a ring 
of the sun appears around the edges of the moon : 
and a central eclipse of the sun will alwavs be an 

E 



40 GRAMMAR OF ASTRONOMY. 

annular one, if the distance of the moon from the 
earth be greater than its mean distance. 

10. An eclipse of the moon is the obscuration 
of her light, occasioned by the interposition of the 
earth between the sun and moon ; which can only 
happen at full moon, or when the moon is in op- 
position to the sun. 

11. The shadow of the earth is a cone, the base 
of which is on the surface of the earth, and the 
moon is eclipsed by this cone or shadow. — This is 
evident from the sun's being larger than the earth. 

12. A partial eclipse of the moon is when a part 
of the moon's disk is within the shadow of the 
earth ; total, when all her disk is covered by the 
shadow ; and central, when the shadow of the 
earth falls upon the centre of the moon's disk. 

13. Were the orbit of the moon, and that of the 
earth, in the same plane, there would be an eclipse 
of the moon at every full moon, and an eclipse of 
the sun at every new moon : but the orbit of the 
moon makes an angle with the orbit of the earth, 
of about 5£ degrees. The places at which these 
lines intersect are called the moon's nodes. 

14. Eclipses of the satellites of Jupiter fre- 
quently happen, and are of the utmost importance 
in calculating the longitudes of places, because 
their immersion and emersion take place at the 
same instant of time, on all parts of the earth's 
surface. 



1 



GRAMMAR OF ASTRONOMY. 



4T 



A TABLE OF ECLIPSES. 



Years 



1825 



1826 



1827 
1828 

1829 



1830 



1831 

1832 
1833 



1834 



1835 



IP 
# 

DP 

IT 
IT 

m 
® p 

© 
© 
®p 

(DP 

© 
m 

® T 

(DP 
© P 
© 
I P 
® P 

» 
i r 

® T 

® P 
© 
® P 



1836 



1837 



1838 



1839 



® P 
® T 

© 

® r 
® p 

® p 

© 

© 



Months and 
Days. 



June 1 
June 16 
Nov. 25 
May 21 
Nov. 14 
Nov. 29 
Nov. 3 
April 14 
Oct. 9 
March 20 
Sept. 13 
Sept. 28 
Feb. 23 
March 9 
Sept. 2 
Feb. 26 
Aug. 23 
July 27 
Jan. 6 
July 2 
July 17 
Dec. 26 
June 21 
Dec. 16 
May 27 
June 10 
Nov. 20 
May 1 
May 15 
Oct. 24 
April 20 
May 4 
Oct. 13 
April 10 
Oct. 3 
March 15 
Sept. 7 



Time. 



0J M 

o£ 

4i 
«4 

nj M 

5 A 

91 M 

0J M 

2 A 

7 M 

2A M 



104 M 

24 
8 

1 

7 

10 



84 M 

M 

A 

M 



14 
li 
n 

8£ M 
2j A 
1| A 
9 A 
74 A 

114 A 
2J M 
3 A 
2J A 

10A A 



Fears 



1840 



1841 



1842 
1843 



1844 
1845 



® P 

© 
® P 

® 



® 

® r 

© 

® i 
® P 
® P 

® J 
® t 



® I 
® P 

46 1 © 
© 



184: 



1848 



1849 



1850 
1851 



1852 



® P 

© 
© 

m t 

® - 
© 
© 
® p 
® p 
© 
© 

© p 
® p 

® T 
® T 

© 



Months and 
Days. 



Feb 17 
March 4 
Aug. 13 
Feb. 6 
Feb. 21 
July 18 
Kug. 2 
Jan 26 
Julv 8 
July 22 
June 12 
Dec 7 
Dec. 21 
May 31 
Nov. 25 
May 6 
May 21 
Nov. 14 
April 25 
Oct -0 
March 31 
-ept 24 
Oct. 9 
March 19 
Sept. 13 
Sept. 27 
Feb. 23 
March 9 
Sept. 2 
Feb. 12 
Aug. 7 
Jan. 17 
July 13 
July 28 
Jan. 7 
July 1 
Dec 11 



Time. 

2 A 
4 M 
74 M 
24 M 



11 

2 

10 
6 

7 
II 

8 



M 
A 

M 
A 
xM 
M 
M 



04 M 

54 M 

11| A 

j M 

M 

A 

M 

A 



104 

44 

l 

54 

84 M 

94 
3 



A 
A 

94 M 

94 A 

6£ M 

10 M 

14 
1 

54 



M 
M 

A 

64 M 



10 

5 



74 M 

n a 

6* M 
3| A 

4 M 



i8' GRAMMAR OF ASTRONOMY'. 

O/ IVifcs. 

1. Tide is defined to be a periodical motion, or 
flux and reflux, of the waters in seas and rivers, 
caused by the attractive action jj'f the sun and 
moon upon the ocean. 

2. The waters ebb and flow twice in every lu- 
nar day, or periodical return of the moon to the 
same meridian, making nearly two ebb and two 
flood tides every day. 

3. The ocean covers more than half of the 
earth's surface; and this large body of water i» 
continually in motion, ebbing and flowing alter- 
nately. 

4. The water flows for the space of six hours, 
and apparently rests for a few minutes, when it is 
called high water. It then subsides, flowing back' 
six hours, when the rivers resume their natural 
course, and the tide is said to be at low water- 
mark. 

5. The time of high water is not always the 
same, but is about three quarters of an hour later 
every day, for the space of about 30 days, when it 
begins again as before.* 

Obs. We will suppose, at a certain place it is high- 
water at 3 o'clock in the afternoon on the day of new 
moon ; the next day it will be high water 3 quarters of 
an hour after three ; and the next succeeding clay, about 
£ past 4 ; and so on to the next new moon, when it will 
again be high water at 3.— This answers to the motion 
of the moon, for the moon rises every da}' about 45 mi- 
nutes later than the day preceding : or, it is 24 hours 
45 minutes from the time of the moon's appearing on 

* This retardation actually varies from 24 hours 30 miuutes to 25 hours 
30 minutes. 



GRAMMAR OF ASTRONOMY. 49 

any meridian to the time at which it appears on the same 
meridian again. 

According to the Newtonian^principles of attraction, 
these phsenomena are thus explained :— The waters on 
the side of the earth next to the moon are more attract- 
ed than the central parts by the moon ; and these again 
more than the waters on the opposite. — Therefore the 
distance between the earth's centre, and the waters on 
its surface under the moon and opposite to it, will be in- 
creased To explain this more particularly, though the 
diameter of the earth bears a considerable proportion to 
its distance from the moon, yet this diameter is nothing, 
compared with the earth's distance from the sun ; con- 
sequently the difference of the sun's attraction on the 
sides of the earth next to him, will be far less than the 
difference of the moon's attraction on the sides opposite 
to her ; therefore the moon must raise the waters higher 
than they could be raised by the sun. 

6. Sir Isaac Newton determined the influence 
of the sun on the earth to be three times less than 
that of the moon. 

7. The tides, being the joint production of the 
sun and moon, are properly two, solar and lunar, 
whose effects are joint or opposite, according to 
the situation of the bodies by which they are 
effected. 

8. When the sun and moon act together, as at 
new and full moon, the flux and reflux become 
considerable, and are called spring tides. But 
when one tends to elevate, and the other to de- 
press the waters, as at the moon's first and third 
quarters, the flux and reflux will be diminished : 
these are called neap tides. 

9. The sun's being farther from our hemisphere 
in March and September, than in February and 
October, is the reason that the greatest tides hap- 
pen a little before the vernal, and a little after the 
autumnal equinox. 

10. When the moon is in the equator, the tides 

E 2 



50 GRAMMAR OF ASTRONOMY. 

are equally high in both parts of the lunar day J 
which is 24 hours 48 minutes ; but as she declines 
toward either pole, the tides are alternately higher] 
or lower, in northern and southern latitudes. 

11. The tides are so retarded in their passage 
through channels, and so affected by capes and 
headlands, as to happen variously at different 
places. 

12. The tide raised in the German ocean, when 
the moon is 3 hours past meridian, takes 3 hours 
to arrive at London bridge. 

13. Lakes have no tides, because every part is 
attracted alike. 

14. The Mediterranean and Baltic seas have 
but small elevations, on account of the narrowness 
of the inlets by which they communicate with the 
ocean. 

15. The tides often rise at the bay of Fundy, 
and the gulf of St. Lawrence, to the astonishing 
height of 50 or 60 feet. 



CHAPTER XIX. 

Of Atmosphere, 

1. Atmosphere is an elastic fluid surrounding 
the earth. It is necessary not only to the comfort 
and convenience of life, but to the support of life 
itself, and to the constitution of matter in general. 

2. The atmosphere is perceptible to the height 
of about 45 miles above the surface of the earth ; 
and consists of nitrogen, oxygen, and carbonic 
acid gas. 

3. The average weight or pressure of the at- 
mosphere upon every foot of the earth's surface, 
is 2100 pounds As we ascend it becomes more 



GRAMxMAR OF ASTRONOMY, 51 

rarefied, and less dense ; consequently the pressure 
is not so great upon high ground, as it is upon 
low. 

4. As the earth, and the ambient parts of the 
atmosphere, revolve together uniformly about the 
common axis, the different parts of both have a 
centrifugal force, whose tendency is more consi- 
derable, and a centripetal force, whose tendency 
is less considerable, according as the parts are 
more or less remote from the axis ; hence the 
figure of the atmosphere is that of an oblate sphe- 
roid, since the parts corresponding to the equator 
are farther from the axis than those at the poles, 

Obs. The pressure of the atmosphere sustains a co- 
lumn of quicksilver, in the tube of a barometer, of about 
30 inches in height ; hence the whole weight is equal to 
a column of quicksilver 30 inches in height, and of equal 
base ; and as a cubical inch of quicksilver weighs near- 
ly Jib. avoirdupois, every square inch of surface sus- 
tains 15 lbs. of atmosphere. From this it is computed, 
that the pressure of this fluid on the surface of the earth, 
is< equal to that of a globe of lead 64) miles in dfameter ; 
consequently the pressure upon the human body, cannot 
be less than 32400Ibs. which would crush it to atoms 
were it not filled with some elastic fluid, which counter- 
balances this weight. 

Were the atmosphere not elastic, but every where 
equable, its height would be determined from its density, 
and the column of mercury it would counterbalance in 
the tube of a barometer. The height of the atmosphere 
would then be i 1040 times thirty inches, or about 54 miles; 
but the air being very elastic, and the more it is com- 
pressed, the less space it occupies, it follows that in the 
upper regions, as it ascends it must become more rarified, 
till it extends to an infinite height. At the height p£ 
3J miles, the density of the atmosphere is twice as much 
rarefied as at the earth's surface ; and at 7 miles elevation, 
four times as-much; and so on in a geometrical progression. 
From this calculation it might be proved, that a cubic 
inch of the air we breathe, would be so rarefied at the 



52 GRAMMAR OP ASTRONOMY 

height of 5€0 miles, as to fill a sphere, equal in diameter 
to the orbit of Saturn : this however may be considered 
almost an idle speculation. 



CHAPTER XX. 

Of Wind. 

1. Wind is a body of the atmosphere put in 
motion. We may attribute the general cause of 
wind, to heat and electricity. 

2. Currents of winds thus produced, may be 
permanent and general, extending over a large 
portion of the globe, periodical, as in the Indian 
ocean, or variable, as in temperate climates. 

3. Permanent and general winds blow nearly 
in the same direction. In the Atlantic and Paci- 
fic oceans they generally follow the course of the 
sun, to the distance of about 28° on either side 
of the equator. By navigators they are generally 
called trade winds. 

4. Periodical winds , or monsoons, blow in one 
direction for about 6 months, then change and 
blow in the opposite direction 6 months ; namely, 
from April to September they blow southward, the 
whole length of the Indian ocean, between 28° 
north and 28° south latitude, and from October to 
March, they blow northward. 

5. Variable winds are such as blow in every 
possible direction. 

6. Hermattan are singular winds, blowing pe- 
riodically, from the interior of Africa towards the 
Atlantic. 

7. Sirocco or Siroc blow in Italy, and resemble, 
in some measure, the Hermattan, but are very 
hot and unhealthy. 



■M 



GRAMMAR OF ASTRONOMY, 



bo 



8. The Samiel blow in the deserts of Bagdad^ 
and are of all others the most to be dreaded in 
their effects. 

9. The Simoom blow in the sandy deserts of 
Africa. 

10. The following table shows the velocity and 
pressure of the winds, according to their different 
appellations. 



Vcl.city of the Wind, 



Miles in \ Feet in one 
one hour, second. 



too 




36.67 
44- 01 ( 
51.34 S 
58.68? 
66. 01 S 
73.35 
88.02 
117.36 



146. 70 



Perpendicular 
force on the 
quare foot, 
in pounds 

avoirdupois. 



Common appellations of the 
Winds. 



49. 200 



Hardly perceptible 

Just perceptible. 

^ Gentle pleasant 
( wind. 

Pleasant brisk gale 
Very brisk. 
High winds. 

Very high. 

A storm or tempest. 

A great storm. 

A hurricane. 

A hurricane that 
tears up trees, and 
carries buildings, 
I &c, before it. 



54 GRAMMAR OF ASTRONOMV 



CHAP^EE XXX. 

Of Climates. 

1. A climate, reckoning from the equator to 
either of the polar circles, is a space upon the sur- 
face of the earth, included between two such pa- 
rallels of latitude, that the longest day in the one, 
exceeds the longest of the other, by half an hour ; 
but from the polar circles to the poles, climates 
are measured by the increase of a month. 

2. There are twenty-four climates between the 
equator and each of the polar circles, and six from 
each polar circle to its respective pole. 

Obs. We must not infer from the definition above, 
that the temperature is always the same in the same cli- 
mate — quite to the contrary ; for elevated situations, 
woods, morasses, lakes, sandy deserts, &c. have much 
effect on the atmosphere. Thus, some of the mountains 
in Asia and South America, although in the torrid zone, 
are at their summits perpetually covered with snow, 
which cools the air for some distance around. 



I. Climates between the Equator and the Polar 




Circles. 




Climate. 


Ends in lati- 


Where the longest 


Breadth of the 




tude 


day is 


Climates. 




o ' 


H M. 


o t 


I. 


8 34 


12 30 


8 34 


II. 


16 44 


13 


8 10 


in. 


24 12 


13 30 


7 28 


IV. 


30 48 


14 


6 39 


V. 


36 31 


14 30 


5 43 



GRAMMAR OF ASTRONOMY. 



JO 



Climates , <$*c. 


continued. 




Climates. 


Ends in ait ude 


Where the long- 
est day is 


Breadth of the 
Climates. 




o > 


H M. 


o / 


VI. 


41 24 


15 


4 53 


VII. 


45 32 


15 30 


4 8 


VIII. 


49 2 


16 


3 30 


IX. 


51 59 


16 30 


2 57 


X. 


54 30 


17 


2 1 


XI. 


56 38 


17 30 


2 38 


XII. 


58 27 


18 


1 49 


XIII. 


59 59 


18 30 


1 32 


XIV. 


61 18 


19 


1 9 


XV. 


62 26 


19 30 


1 18 


XVI. 


63 22 


20 


56 


XVII. 


64 10 


20 30 


48 


XVIII. 


64 50 


21 


40 


XIX. 


65 22 


21 30 


32 


XX. 


65 48 


22 


26 


XXI. 


66 25 


22 30 


17 


XXII. 


66 21 


3 


16 


XXIII. 


66 29 


23 30 


8 


XXIV. 


66 32 


24 


3 


II. Climates t 


»etween the 


Polar Circ 


les and the 




Pole 


s. 




Climates. 


Ends in latitude 


Where the long- 
est day is 


Br-adth of the 
Climates 




o / 


Days. Month. 


O ; 


XXV. 


67 18 


30 or 1 


46 


XXVI. 


69 33 


60 2 


2 15 


XXVII. 


73 5 


90 3 


3 32 


XXVIII. 


77 40 


120 4 


4 35 


XXIX. 


82 59 


150 5 


5 19 


XXX. 


90 


180 6 


7 1 



56 GRAMMAR OF ASTRONOMY 



Of the Aurora Borealis, Milky-way, and Zodiacal 
Lights. 

1. Aurora Borealis, or the northern light, is 
a meteor, which appears in the northern part of 
the heavens, on cold frosty evenings in the winter 
season. 

2. It generally appears in streaks of }^ellow and 
reddish colour, the coruscations rising from the 
horizon, in the form of pyramids, and shooting 
upwards toward the zenith. — The flashes some- 
times have the appearance of contending armies 
in the heavens. 

3. The Aurora Borealis is attributed to the 
effect of electricity in the -atmosphere. It is not 
unfrequently seen in this country, but with much 
less brilliancy than in the more northern regions. 

4. This light, in the northern parts of Europe, 
America, and Asia, is frequently equal to the light 
of the full moon, and supplies, in a great measure, 
the absence of the sun. The streaks are supposed 
bv Euler to extend several thousand miles. 

Obs. " Dr. T. L. Thieneman, who spent the winter 
of 1820 and 1-821 in Iceland, made numerous observa- 
tions on the polar lights. He states the following as 
some of the general results of his observations : f . The 
polar lights are situated in the lightest and highest clouds 
of our atmosphere. 2. They are not confined to the 
winter season or to the night, but present in favourable 
circumstances at all times, but are only distinctly visible 
during the absence of the solar rays. 3. The polar lights 
have no determinate connexion with the earth. 4. He 
never heard any noise proceed from them. 5. Their 
common form, m Iceland, is the arched, and in a direc- 



GRAMMAR OF ASTRONOMY. 57 

tLGii from N. E. and W. S W, 6. Their motions are 
various, but always within the limits of the clouds which 
contain them." 

5. The Galax r, or Milky-way, is a bright, lu- 
minous circle of some breadth in the heavens, and 
distinguished by its superior brilliancy. 

6. It is composed of a vast number of stars, too 
minute to be seen by the naked eye, but with a 
good telescope, they may be observed in almost 
countless numbers. 50,000 were enumerated by 
Dr. Herschel in a small part, only 15 degrees in 
length and 2 in breadth. 

7. Zodiacal Light is a brightness sometimes 
observed in the zodiac, resembling that of the 
galaxy. It appears only at certain seasons, name- 
ly, towards the end of w r inter, and in spring after 
sunset; or before sunrise in autumn and the be- 
ginning of winter. Its form is that of a pyramid 
lying lengthwise, with its axis along the zodiac, its 
base being placed obliquely with respect to the 
horizon. 



OBAPTB& XXIIX. 

Of Time. 

1. Time is the measure of duration, and is di- 
vided into years, months, days, hours, minutes, 
and seconds. 

2. A year is the space of time occupied by the 
earth, in performing its revolution around the sun, 
through the 12 signs of the zodiac. A year is of 
two kinds, tropical and sidereal. 

3. A tropical or natural year is the time which 
the earth takes to pass through the fixed zodiac. 

F 



58 GRAMMAR OF ASTRONOMY . 

which, as has been before observed, is 365 days 
5 hours 48 minutes 45^ seconds. 

4. A sidereal or astral year is the time that the 
sun apparently occupies in passing from a fixed star 
to its arrival at the same star again ; and is 365 days 
5 hours 9 minutes 17 seconds in length. 

5. The common or civil year is commonly 
reckoned at 365 days ; but the true tropical year 
consists of about 365^ days ; hence if the civil 
year be made to consist of 365 days, every fourth 
year must be 366 days. 

6. A common civil year is divided into twelve 
months, of which one has 28 days ; seven have 
31 ; and four 30 days each. The one that has 
28 days, has 29 every fourth year. 

7. A day is that portion of time which the earth 
takes to complete an entire rotation on its axis ; 
and is divided into natural, civil, artificial, astro- 
nomical, and sidereal. 

8. A natural day is the time the earth occupies 
to revolve once on its axis. 

9. A civil day is twice 12 hours. In England, 
and in the United States, it is reckoned from mid- 
night to midnight. 

Obs. The ancient Athenians, the Jews, &c. began 
their day at sun- setting, which custom is followed by the 
modern Austrians, Bohemians, Silesians, Italians, and 
Chinese. The ancient Babylonians, Persians, Syrians, 
and most of the eastern nations, began their day at sun- 
rising. The Egyptians and Romans began their day at 
midnight, and are followed by the English, the Ameri- 
cans, French, Germans, Spanish, Dutch, and Portu- 
guese. The Arabians begin their day at noon like the 
modern atronomers 

10. An artificial day is the interval between 
the rising and the setting of the sun. 

11. An astronomical day is the time whcili 



GRAMMAR OF ASTRONOMY. b l 3 

elapses from the sun's appearing on a meridian to 
the time of his appearing on the same meridian 
again. It is reckoned from noon to noon. 

12. A sidereal day is the time which the earth 
requires to perform a complete rotation on its axis 
from a fixed star to the same star again. 

13 An hour is the 24th part of a day, a minute 
the 60th part of an hour, and a second the 60th 
part of a minute. 

14. Mean time is that shown by a well-regulated 
clock, dividing the day into 24 equal parts. 

15. Apparent time is that shown by a correct 
sundial. 

16. Equation of time is the difference between 
mean and apparent time ; or the time shown by a 
clock and that by a sundial. 

Obs. A true solar daj^ is subject to a continual varia- 
tion, on account of the obliquity of the ecliptic, and the 
unequal motion of the earth in its orbit ; the duration 
thereof sometimes exceeds, and at others falls short, of 
24 hours ; and the variation is greatest about the first of 
November, when the solar cby is 16 min. 15. sec. less 
than 24 hours, as shown by a clock. 

There are, in the course of the year, as many mean 
solar days as there are true ones, the clock being as 
much faster than the sundial on some days of the year, 
as the sundial is faster than the clock en others. Thus 
the clock is faster than the sundial from the 24th of 
December to the 15th of April, and from the 16th of June 
to the 31st of August; but from the 15th of April to the 
16th of June, and from the 3 1st of August to the 24th of 
December, the sundial is faster than the clock. 

When the clock is faster than the sundial, the true 
solar day exceeds 24 hours ; but when the clock is slow- 
er than the sundial, the true solar da} r is less than 24 
hours. When the clock and sundial agree, which hap- 
pens about the 15th of April, 16th of June, 31st of Au- 
gust, and 24th of December, the true solar day is exnr' 
}v 24 hours. 



60 GRAMMAR OF ASTRONOMY. 

CHAPTER XXXV. 

Of the Globes. 

1. Artificial globes are of two kinds, terrestrial 
and celestial. 

2. The terrestrial globe is a spherical body 
intended to represent the true figure of the earth, 
the relative situations of different countries, seas, 
lakes, and rivers ; and to illustrate the phenomena 
arising from its diurnal motion, which is from west 
to east. 

3. The celestial globe is intended to represent 
the face of the heavens; the places of the fixed 
stars, as situated in their several constellations ; 
and the apparent diurnal motion of the sun and 
stars, as they would appear to a spectator in the 
centre of the globe. The diurnal motion of this 
globe is from east to west. 

4. The globes commonly used are composed of 
plaster, on which the maps, or descriptions, are 
pasted. When finished, they are hung in a brass 
meridian, with an hour circle, and a quadrant of 
altitude, and fitted into a wooden horizon. 

5. The axis of the earth is an imaginary line 
passing through the centre of it, upon which it is 
supposed to turn, and about which all the heaven- 
ly bodies appear to perform a diurnal revolution. 
This line is represented by the wire which passes 
through the middle of the globe, from north to 
south. 

6. The poles of the earth are the two extremi- 
ties of the axis, where it is supposed to cut the 
surface of the earth. One of these extremities is 



GRAMMAR OF ASTRONOMY. 6l 

called the north or arctic pole, and the other, the 
south or antarctic pole. 

7. Ten principal circles of the sphere, are mark- 
ed on the globes, 6 great, and 4 small ones. The 
great circles divide the globe into equal parts ; the 
small circles, into unequal parts. 

8. The great circles are, the horizon, meridian, 
equator, ecliptic, and the two colures. 

9. The small circles are the two tropics and the 
two polar circles. The tropic of Cancer is drawn 
23° 28' north latitude : the tropic of Capricorn is 
drawn 23 b 28' south latitude. The arctic circle is 
23° 28' south of the north pole ; and the antarctic 
circle 23° 28' north of the south pole. All of 
these circles are parallel to the equator. 

10. Of the circles of the sphere, some are 
fixed, always keeping the same position ; others 
moveable, according to the position of the ob- 
server. 

11. The horizon is the broad wooden circle 
surrounding the globe, and dividing it into two 
equal parts, called upper and lower hemispheres. 

12. On the face, or flat side of the horizon are 
described 8 concentric circles. The first circle is 
marked amplitude ; the second, azimuth : on these 
are reckoned the amplitude and azimuth of the ce- 
lestial bodies. The third contains the 32 points 
of the compass. The fourth circle contains the 
12 signs of the zodiac. The fifth contains the 
degrees of the signs, each sign comprehending 30 
degrees. The sixth contains the days of the month, 
corresponding to each degree. The seventh cir- 
cle contains the equation of time. The eighth 
circle contains the 12 calendar months of the year. 

13. The brass meridian is a ring of brass divid- 
ed into 360 decrees, each quadrant or quarter 

F 2 



02 GRAMMAR OF ASfWSOMY. 

containing 90 degrees. This circle divides the 
globe into two equal parts, called the eastern and 
western hemispheres. 

14. The equator* is an imaginary line extending 
around the centre of the globe from east to west, 
equidistant from the poles, and dividing it into 
northern and southern hemispheres* 

15. The longitude of places is marked on the 
equator eastward and westward from the meridian 
of London. Latitude is reckoned from the equa- 
tor north and south. 

16. The ecliptic is an imaginary line drawn 
through the middle of the zodiac, in which the 
earth makes its annual revolution round the sun; 
or. it is the apparent path of the sun among the 
fixed stars. 

17. The ecliptic forms an angle of 23° 28' with 
the equator ; the points of intersection are called 
the equinoctial points. On the ecliptic are mark- 
ed the 12 signs of the zodiac. 

18. The coheres are two great circles, supposed 
to intersect each other at right angles, in the poles 
of the world, and to pass through the solstitial and 
equinoctial points of the ecliptic. The equinoc- 
tial points are Aries and Libra ; and the solstitial 
points, Cancer and Capricorn. These divisions 
of the ecliptic mark the seasons of the year. 

19. The quadrant of altitude is a thin pliable 
plate of brass, divided into 90 degrees, answering 
exactly to a quadrant of the meridian, and has a 
notch, nut, and screw, to fix it to the brazen me- 
ridian, in the zenith of any place, where it turns 
round a pivot, and supplies the place of vertical 
circles. 

20. The hour circle is a flat ring of brass, divid- 

* The equator Is called the equinoctial on tire celestial globe. 



GRAMMAR OF ASTRONOMY 

M Into 24 equal parts, or hour distances ; and on 
the pole of the globe is fixed an index that turns 
with it, and points out the hours upon the hour 
circle.* 

21. Parallels of latitude are small circles drawn 
on the terrestrial globe every ten degrees parallel 
to the equator. 

22. Meridians of longitude are semicircular lines 
extending from one pole to the other, and crossing 
the equator at right angles. The first meridian, 
or that from which longitude is reckoned, is the 
meridian of the royal observatory at Greenwich, 
near London. 

23. The zodiac^ on the celestial globe, extends 
8 degrees on each side of the ecliptic^ forming a 
girdle, or belt, within which space all the planets 
perform their annual revolution, except Ceres and 
Pallas. 

'24. The sun apparently moves through the 
zodiac at the rate of nearly a degree every day. 
The sun in his apparent movement through the 
ecliptic enters the signs as follow : 

Spring Signs. Summer Signs. 

r r Aries, 21st of March. || ^ Cancer, 21st of June. 

$ Taurus, 19th of April, jj a Leo, 22d of July. 

II Gemini, 20th of May. j| T$ Virgo, 22d of August. 

The signs above are called northern signs, being 
north of the equator ; consequently when the son 
is in any of these signs, his declination is north. 

Autumnal Signs. Winter Signs. 



=5= Libra, 23d of September. 
Til Scorpio, 23d of October. 
$ Sagittarius, 22d of N07. 



V3Capricornus,21stof Dec, 
ss Aquarius, 20th of Jan. 
X Pisces, l9thof Feb. 



* So^e nrwWn globes have a moveable hour circle, ana* the tiofe on 
these is shown by the cress jiieruiiai.. 



04 GRAMMAR OF ASTRONOMY- 

The autumnal and the winter signs are southern 
signs: when the sun is in any of these signs, his 
declination is south. The declination of the sun 
can never exceed 23° 28' ; that of a star 90° ; and 
that of a planet 30° north or south. 

25. The analemma is a projection of a sphere 
on a plane of the meridian, made by straight lines, 
which are supposed to be at an infinite distance 
in the east or the west point of the horizon. 



ASTRONOMICAL 

AND 
PERFORMED BY THE GLOBES. 

Problems performed by the Terrestrial Globe, 

PROBLEM I. 

To find the latitude of any place. 

Rule. Bring the given place to the brass me- 
ridian, and the degree over it, counting from the 
equator, is the latitude required. 

1. Required the latitude of Washington, 
New-York, Baltimore, 

St. Petersburg, Stockholm, 

Philadelphia, Ispahan, 

Edinburgh, Amsterdam, 

Constantinople, Cape Horn, 

London, Cape of Good Hope, 

Boston, Prague, 

Lisbon, Liverpool, 

Naples, Halifax. 

Obs. The latitude of places cannot be determined on 
small globes nearer than about a quarter of a degree ; 
but on large globes each degree on the brass meridian 
being divided into three equal parts, the latitude may 
be determined as near as 10 minutes, 



J 



66 GRAMMAR OF ASTRONOMY. 

PROBLEM XX. 

To find the longitude of any given place. 

Rule. Bring the place to the graduated side 
of the hrass meridian, and the degree under it on 
the equator, counting from the meridian of Lon- 
don, is the longitude required. 

1. Required the longitude of Washington, 



New-Orleans, 


Moscow, 


Boston, 


Warsaw, 


Dublin, 


Madrid, 


Bengal, 


Madras. 


Norfolk, 


Lisbon, 


Tripoli, 


Quito, 


Vienna, 


Cairo, 


Athens, 


Aleppo, 


Batavia, 


Portland. 



Obs. On Bardin's Globes there are two rows of figures 
above the equator, but the lower is always used in reck- 
oning longitude. Adam's globes have also two rows of 
figures above the equator, the lower line is used when 
the place lies on the left of the meridian of London ; and 
the upper line is used when the place lies on the right 
of the meridian of London. 



PROBLEftZ XXX. 

To find all places having the same latitude as any 
given place. 

Rule. Find the latitude of the given place; 
turn the globe on its axis, and all those places 



GRAMMAR OF ASTRONOMY. 67 

passing under the observed latitude, are the places 
required. 

1. Required those places having nearly the 
same latitude as Philadelphia. 

Ans. Madrid, Constantinople, Naples, &c. 

2. Required those places having nearly the 
same latitude as New Orleans. 

3. Required those places having nearly the 
same latitude as Edinburgh. 

4. Required those places having nearly the 
same latitude as Port Royal in Jamaica. 

5. Required those people having the same 
length of day and night as the inhabitants of New- 
York. 

6. Required those people having the same 
length of day and night, as the inhabitants of 
London. 

7. Required those places having the same lati- 
tude as Calcutta. 

8. Required those places having the same lati- 
tude as Quito. 

9. Required those places having the latitude of 
Washington. 

10. Required those people having the same 
length of day and night, as the inhabitants of 
Paris. 

Obs. — All places in the same latitude have the same 
length of day and night. 



PROBLEM IV. 

To find all places having the same longitude as any 
given place. 

Rule- Bring. the given place to the brass me- 



t>8 GRAMMAR OF ASTRONOMY. 

ridian, and all the places under the same edge 
have the same longitude. 

1. What places have the same longitude as 
Dantzic ? 

Ans. The cape of Good Hope, Presburg, Stockholm, &c„ 

2. Required those places having the same lon- 
gitude as Quebec. 

3. Required those places having the same lon- 
gitude as London. 

4. Required those people having noon at the 
same time as the inhabitants of New-York. 

5. Required those places having midnight at 
the same time as at Washington. 

6. Required those people having sunrise at the 
same time as the inhabitants of St. Louis. 

7. Required those people having sunset at the 
same time as the inhabitants of Archangel. 

8. Required those places having sunset when 
it is sunrise at Vienna. 

9. When it is noon at Alexandria, at what 
places is it midnight ? 

10. Required those places having the same lon- 
gitude as the Pelew Islands, Pekin, London, Bos- 
ton, and Portland. 

Obs. Places on the meridian of London, and its op» 
posite meridian, marked 180°, may be said to have no 
longitude, i. e. they are in neither east nor west longi- 
tude. All places on the same meridian from 66° 28^ 
north, to 66° 28' south latitude, have noon, midnight, 
sunrise, and sunset at the same time. 



GRAMMAR OF ASTRONOMY* 69 



PROBLSI*£ V. 

To find any place having the latitude and longitude 

given. 

Rule. Bring the given degree of longitude to 
the brass meridian, and under the given degree of 
latitude, will be the place required. 

1.- Required the place having 151° east longi- 
tude, and 34° south latitude. 

Ans. Botany Bay. 

2. Required the place situated in about 6° west 
longitude, and 16° south latitude. 

Ans. St. Helena. 

3. Required those places having the following 
latitudes and longitudes. 



Latitude. 


Longitude. 


Latitude. 


Longitude. 


34°29'S. 


18°23'E. 


32°25'N. 


55°50'E. 


64 34 N. 


38 58 E. 


34 35 S. 


58 31 W. 


31 13 N. 


29 55 E. 


3 49 S. 


102 10 E. 


52 22 N. 


4 51 E. 


32 38 N. 


17 6W. 


55. 58 N. 


3 12 W. 


36 5 N. 


5 22 W. 


48 12 N. 


16 16 E. 


22 54 S. 


42 44 W. 


50 6N. 


5 54 W. 


8 32 N. 


81 11 E, 



PROBLEM VI. 

To find the latitude and longitude of any given 

place. 

Rule. Bring the given place to the brass meri* 
dian ; the degree over it will be the latitude, and 

G 



70 GRAMMAR OF ASTRONOMY. 

the degree on the equator, cut by the meridian, 

will be the longitude required. 

1. Required the latitude and longitude of 
Liverpool, Constantinople, 

Leghorn, New-York, 

Gibraltar, Washington, 

Copenhagen, Havanna, 

Canton, Savannah, 

Aberdeen, Madrid, 

Botany Bay Stockholm, 

St. Helena, Dublin, 

Alexandria, Lisbon, 

Bombay, Oporto, 

Cayenne, Rome, 

Ephesus, Elba. 

Obs. The problem above is only a combination of 
the first and the second. 

As all latitudes are reckoned from the equator, and 
all longitudes from the first meridian, it is evident, (hat 
the point of the equator cut by the first meridian, has 
neither latitude nor longitude. The greatest latitude is 
90 degrees, because no place is more than 90° from the 
equator. The greatest longitude is ltiu degrees, be- 
cause no place is more than 180 degrees from the first 
meridian. 



FR08&B1K VII. 

To find the difference of latitude between any two 
given places* 

Rule. Find the latitudes of both places ; if the 
latitudes be both north, or both south, subtract the 
less from the greater, and the remainder will be the 
difference of latitude ; but if one of the latitudes 
be north, and the other south, add them together^ 



GRAMMAR OF ASTRONOMY, yfl 

and their sum will be the difference of latitude re» 
quired : or, count the number of degrees on the 
brass meridian between the observed latitudes of 
the two places. 

1. Required the difference of latitude between 
Buenos Ayres and Madrid. 

Arts, 75 degrees. 

2. Required the difference of latitude between 

Quebec and New Orleans, 

Washington and Quebec, 

Mexico and Washington, 

New-York and London, 

Boston and Liverpool, 

Baltimore and Edinburgh, 

Lima and St. Petersburg, 

Paris and Calcutta, 

Archangel and Moscow, 

Constantinople and Algiers, 

Rome and Aberdeen, 

Vienna and Alexandria, 

Cape Horn and Cape of Good Hope, 

Copenhagen and Stockholm, 

Oporto and Londonderry. 



To find the difference of longitude between any two 
given places. 

Rule. Find the longitudes of both places, if 
the longitude of one be east, and the other west, 
add them together, and their sum will be the diffe- 
rence of longitude;* but if both be east, or both 

* When the sum of the two longitudes, exceeds J 80°, subtract it front 
560°, and the remainder will be the difference of longitude . 






72 GRAMMAR OP ASTRONOMY. 

west, subtract the less from the greater, and the 
remainder will be the difference of longitude re- 
quired. 

1 . Required the difference of longitude between 
Owhyhee and Botany Bay. 

Ans. 52| degrees. 

2. Required the difference of longitude between 

Mexico and Washington, 

London and New-York, 

Constantinople and London, 

Mount Hecla and Mount Etna, 

Batavia and Bombay, 

Gibraltar and Behring's Straits, 

Paris and Glasgow, 

Cordova and Londonderry, 

Portland and St. Louis, 

St. Louis and the mouth of Columbia river, 

St. Helena and Elba, 

Cape, Ortegral and Cape Verd, 

Calcutta and Delhi, 

Cairo and Canton. 



MOB1EM IX. 

To find the distance between any two given places. 

Rule. Bring one of the given places to the 
brass meridian, over which fix the quadrant of al- 
titude; then extend it over the other place, and 
the number, of degrees on the quadrant contained 
between them is the distance in degrees. Or, ex- 
tend the quadrant of altitude over both places, and 
count the number of degrees contained between 
them. Multiply the number of degrees by 69\* 
and the product will be the number of English 



GRAMMAR OP ASTRONOMY. /3 

miles; multiply the degrees by 60, and the pro- 
duct will be geographical miles. 

1. Required the distance between New-York 
and London, 

Boston and New-Orleans, 

St. Petersburg and Archangel, 

Cape St. Roque and Cape Blanco, 

Cape Horn and Cape de la Vela, 

Cape Maize and Cape Bonavista-, 

Aleppo and Calcutta, 

Tripoli and Algiers, 

Jerusalem and Ispahan, 

Bagdad and Smyrna, 

Copenhagen and Cadiz, 

Rome and Astrachan, 

Glasgow and Quebec, 

Lisbon and Naples, 

Halifax and St. Augustine. 

2. Required the distance between the northern 
and the southern, the eastern and the western ex- 
tremities of Europe, Asia, Africa, America, and 
New-Holland. 

Obs. 1 . If the two places be situated in the same la- 
titude, their difference of longitude, multiplied by the 
number of miles in a degree of the given latitude, will 
be the distance between them in miles. 

2. If bo f h places be in the same longitude, their dif- 
ference of latitude, multiplied by the number of miles in 
a degree, will be the distance between them in miles. 



FB.08&BHI X. 

To find the bearing of one place from another. 

Rule. Bring one of the places to the brass 
meridian, screw the quadrant of altitude over it ; 

G2 



#4 GRAMMAR OF ASTRONOMY. 

then extend the quadrant over the other place, 
and the point of its direction, as seen on the hori- 
zon, will be the bearing required. 

1. What direction must a ship sail on a voyage 
from Charleston to Dublin. 

2. Required the bearing between New-York 
and the following places. 



Savannah, 


Brussels, 


St. Louis, 


Athens, 


Philadelphia, 


Stockholm, 


Montreal, 


Bath, 


Boston, 


Belfast, 


Augusta, 


Lima, 


Pensacola,, * 


Buenos Ayres. 


Vienna, 


Cordova, 


Moscow, 


Mexico, 


Paris, 


Utica. 



PRCBXiBSMI XX. 

A particular place, and the hour of the day, given , 
to find all the places where it is then noon, or 
any other given hour. 

Rule. Bring the given place to the brass me- 
ridian, set the index of the hour circle at the given 
hour; then turn the globe on its axis until the 
index points to the upper 12; and to all places 
lying under the brass meridian, it is then noon. 

1. When it is 10 o'clock in the morning at New- 
York, at what places is it noon ? 

Ans. Cape Farewell, &c. 

2. When it is 8 o'clock in the evening at Lon- 
don, at what places is it 10 in the morning? 



GRAMMAR OP ASTRONOMY, 75 

3. When it is 4 o'clock in the morning at Can- 
ton, where is it 4 in the evening? 

4. At Vienna when it is 7 in the morning, wher^ 
is it noon ? 

5. At Edinburgh when it is noon, where is h 
10 in the evening ? 

6. At Washington when it is 6 o'clock in the 
evening, where is it noon ? 

7. Where is it midnight, when it is noon at 
Baltimore ? 

8. When it is noon at Charleston, where is it; 
midnight ? 

9. At the Pelew islands, when it is 4 o'clock in 
the morning, where is it 9 in the evening? 

10. When it is 8 o'clock in the morning at Bos- 
ton, where is it 2 in the evening? 



jraOBKBHE XII. 

The hour of the day at any place give?i, to find 
the hour at any other given place. 

Rule. Bring the first given place to the brass 
meridian, and set the index of the hour circle at 
the given hour ; then turn the globe utitil the other 
place is brought under the brass meridian, and the 
index will point to the hour required. 

1. When it is noon at Washington, what time 
is it at Portland ? 

Ans. J past 12 nearly. 

2. When it is 6 o'clock in the morning at Lon- 
don, what is the time at Cairo ? 

3. When it is 4 o'clock at Oporto, what time is 
it at Rome ? 

4. When it is midnight at Hallowell, what time 
is it at New-Orleans ? 



76 GRAMMAR OF ASTRONOMY. 

5. When it is 10 o'clock in the evening at Am- 
sterdam, what time is it at Archangel ? 

6. When it is 7 o'clock in the evening at Co- 
penhagen, what is the hour at Smyrna 1 

7- When it is 9 o'clock in the morning at Mon- 
treal, what is the time at St. Louis 1 

8. When it is midnight at New- York, what is 
the hour at the mouth of the Columbia river ? 

9. When it is noon at Quito, what is the hour 
at Gibraltar ? 

10. When it is midnight at Pekin, what is the 
time at Damascus 1 

Obs. Some globes have two rows of figures on the 
hour circle, others but one ; this difference in globes 
frequently occasions confusion. 



PB.OB&BHE XIII. 

To find the antipodes, ant&ci 9 and periceci of any 

place. 

Rule. 1. For the antipodes. Bring the given 
place to the brass meridian, observe its latitude; 
set the index of the hour circle at \ 2 ; then turn 
the globe on its axis until the index points to the 
other 12 : in the same latitude in the opposite 
hemisphere are the antipodes required. 

2. For the antceci. Find the latitude of the 
place, and in the same degree of latitude on the 
other side of the equator are the antceci required. 

3. For the periceci. Bring the place to the brass 
meridian, and mark its latitude ; set the index of 
the hour circle at 12 ; then turn the globe on its 
axis until the index points to the other 12; and 



GRAMMAR OF ASTRONOMY. 77 

under the same degree of latitude are the perioeci 
required. 

1. Required the antipodes, antoeci, and perioeci 
of New- York. 

2. Required the antipodes, antceci, and perioeci 
of the following places : 

Alexandria, Cape of Good Hope* 

Mexico, Athens, 

Cape Comorin, Florence, 

St. Helena, Savannah. 

Rome, Upsal, 

Bermudas, Vienna, 

Canton, Isle of Bourbon* 
Botany bay, 

Obs. 1 . The antipodes are those people who lire dis> 
metrically opposite to one another upon the globe, stand- 
ing with feet towards feet, on opposite meridians and 
parallels. Being on opposite sides of the equator thej 
have opposite seasons, winter to one when it is summer 
to the other ; being on opposite meridians, it is noon to 
one, when it is midnight to the other. 

2. The antoeci are those people who live on the same 
meridian, and in equal latitudes on different sides of the 
equator. Being on the same meridian, they have the 
same hours, i. e. when it is noon to one it is noon to the 
other, &c. Being on different sides of the equator, they 
have opposite seasons at the same time. 

3. The perioeci are those who live on the same paral- 
lels of latitude but on opposite meridians ; their latitude 
being the same, but their longitude differing L80°. Be- 
ing in the same latitude, they have the same seasons ; 
but being on opposite meridians, it is noon to the onf* 
when it is midnight to the other* 



a 



GRAMMAR OF ASTRONOMY. 



The month, and day of the month, given, to find 
the surfs longitude, or place in the zodiac ; and 
Ms declination. 

Rule. Find the day of the month in the circle 
of months on the horizon, against which, in the 
circle of signs, is the sun's place in the zodiac ; 
find the same sign and degree in the ecliptic on 
the surface of the globe ; bring it to the meri- 
dian, and the degree over it is his declination. 

1. Required the sun's longitude and declination 
on the 20th of August. 

2. Required the sun's declination and longitude 
on the 4th of July, 

3. Required the sun's longitude and declination 
on the 10th of January, 14th of July, 

4th of February, 7th of August, 

20th of March, 1 1 th of October, 

28th of April, 1 7th of November, 

22d of May, 2 1 st of December, 

1 8th of June, 15th of September. 

Obs. This fproblem may also be performed by the 
celestial globe. 

The analemma may be used, if preferred, instead of 
the circle of signs on the horizon. 

What is called the analemma on the globe, is a narrow 
slip of paper pasted on some vacant place on the globe, 
the length of which is equal to the breadth of the torrid 
zone. It is divided into months, and days of the month, 
corresponding to the sun's declination for every day in 
the year. 

The sun's declination is his distance from the equator 
in degrees ; and is north or south, as the sun's place in 



GHAMMAR OF ASTRONOMY. 



79 



the ecliptic is between the equinoctial and the north or 
the south pole. 



?E01LH1E 3£V. 

To find those places in the torrid zone, having the 
sun vertical on any given day in the year. 

Rule. Find the sun's declination ; turn the 
globe on its axis, and to all places passing under 
the observed degree of the sun's declination, the 
sun will be vertical on that day. 

1 . Required those places having the sun vertical 
on the 



1st of January, 
2d of February. 
4th of March, 
6th of April, 
8th of May, 
10th of June, 
4th of July, 



12th of July, 
14th of August, 
16th of September, 
18th of October, 
20th of November, 
24th of December, 
22d of May. 



To rectify the globe for the latitude, zenith,* and 
sun's place on any given day in the year. 

Rule. 1. For the latitude. — If the latitude be 
north, elevate the north pole as many degrees 
above the horizon, as will correspond with the la- 
titude of the place. If the latitude be south, ele- 
vate the south pole as above directed. 

* The zenith in this sense, is the highest point of the brass meridian 
above the horizon. 



30 GRAMMAR OP ASTRONOMY. 

2. The place is then in its zenith. 

S. Find the sun's place for the given day; bring 
it to the brass meridian, and set the index of the 
hour circle at the upper 12 ; place the north pole 
of the globe due north : the globe will then be in 
the position in which the earth actually is, on that 
day. 

i. Rectify the globe for Boston, on the 16th of 
January, 

London, on the 8th of February, 

Paris, on the 14th of March, 

New Orleans, on the 1 8th of April, 

Cape Horn, on the 22d of May, 

Rome, on the 24th of June, 

New-York, on the 4th of July, 

Baltimore, on the 25th of August, 

Washington, on the 21st of September, 

Mexico, on the 10th of October, 

Lima, on the 12th of November, 

Cape of G. Hope, on the 15th of December. 

Obs. The latitude of any place, is equal to the eleva- 
tion of the nearest pole of the heavens above the horizon 
of that place ; and the poles of the heavens are directly 
over the poles of the earth, each 90° from the equinoc- 
tial line. 

Let us be upon what place of the earth we may, if the 
-limits of our view be not intercepted by hills, we shall 
see one half of the heavens, or 90° every way round 
from that point which is over our heads. Therefore, if 
we were upon the equator, the poles of the heavens would 
lie in our horizon, or limit of our view ; if we go from 
the equator, towards either pole of the earth, we shall 
see the corresponding pole of the heavens rising gra- 
dually above our horizon, just as many degrees as we 
have gone from the equator ; and if we were at either 
of the earth's poles, the corresponding pole of the hea- 
vens would be directly over our heads. Consequently, 
f he elevation ©r height of the pole in degrees, above the 



GRAMMAR OF ASTRONOMY. &l 

horizon, is equal to the number of degrees that the place 
is from the equator. 



p&ob&sbs xvn. 

To find at what hour the sun rises and sets^ and the 
length of the day and night, at any place, on any 
given day in the year. 

Rule. Find the latitude of the place ? and rec- 
tify the globe for the latitude ; find the sun's place 
in the ecliptic, bring it to the brass meridian, and 
set the index of the hour circle at the upper 12 ; 
turn the globe on its axis eastward until the sun's 
place is level with the horizon, and the index will 
point to the hour of the sun's rising Turn the 
globe on its axis westward until the sun is level 
with the western edge of the horizon, and the index 
will point to the hour of the sun's setting. 

The hour of the sun's rising being doubled^ 
shows the length of the night ; and the hour of the 
sun's setting being doubled, shows the length of 
the day. 

1. Required the time when the sun rises and 
sets, and the length of the day and night, at New- 
York, on the 20th of December. 

2. Required the time when the sun rises and 
sets, and the length of the day and night, at War- 
saw, on the 4th of January, 

St. Petersburg, on the 1 8th of February? 
London, on the 10th of March, 
Amsterdam, on the 8th of April, 
Paris, on the 22d of May, 
Londonderry, on the 16th of June, 
Madrid, on the 18th of July, 
H 



82 GRAMMAR OF ASTRONOMY. 

Naples, on the 20th of August, 
Constantinople, on the 17th of September,. 
Aberdeen, on the 14th of October, 
Glasgow, on the 12th of November. 

Obs. The length of the longest day, at all places not 
in the frigid zone, may be found by the above-mentioned 
rule. The longest day in all places in north latitude, is 
on the 21st of June, when the sun is in his greatest de- 
clination north ; and the longest day at all places in 
south latitude, is on the 21st of December, when the sun 
is in his greatest southern declination. 



PROBLEM XVIII. 

To find those days of the year on which the sun 
will be vertical at any given place in the torrid 
zone. 

Rule. Bring the given place to the brass me- 
ridian, and mark its latitude ; then turn the globe 
on its axis, and observe those two points of the 
ecliptic, which pass under that degree of latitude; 
look for these points of the ecliptic, in the circle of 
signs on the horizon, against which, in the circle 
of months, are the days required. 

1. Required those two days of the year on 
which the sun will be vertical at 

Lima, Sierra Leone y 

Mexico. Manilla, 

Havanna, Sandwich Islands., 

St. Helena, Friendly Islands s 

Pelew Islands, Rio Janeiro, 

Quito, Cape Comorin. 

Caraccas, Canton, 

St Salvador. Calcutta. 



GRAMMAR OF ASTRONOMY. S3 



To find the number of miles contained in a degree 
of longitude in any given parallel of latitude. 

Rule. Find the distance, with a pair of com- 
passes, between two meridians differing in longi- 
tude 1 5° in the given parallel of latitude ; measure 
the number of degrees contained in this distance 
on ihe equator; multiply the number of degrees 
found by 4, and the product will be the number of 
geographical miles. Or, find the number of de- 
grees contained between the two meridians 1 5 de- 
grees distant, with the quadrant of altitude, and 
proceed as above directed. 

1. Required the number of geographical miles 
contained in a degree of longitude in the latitude 
of Washington. 

Obs. Any number of geographical miles, may be 
brought into English miles, by multiplying by l9^ and 
dividing by 60. A 

2. Required the number of geographical, and 
English miles contained in a degree of latitude at 

Quito, Edinburgh, 

Mexico, London, 

Charleston, Archangel, 

Boston, Warsaw, 

Quebec, Moscow, 

Mount Hecla, Cape Farewell, 

Constantinople, Madrid, 

I Obs. When Gary's large globes are used, as the me* 



B4 GRAMMAR OP ASTRONOMY. 

ridians are drawn 10° distant, we must read 10 instead 
of 15, and multiply by 6 instead of 4. 

2. On small globes the meridians are drawn 1 5° distant: 
but on large globes, the meridians are generally drawn 
i0° distant. 



JFROBIiElia XX. 

To ascertain how far the inhabitants of any place 
are carried in an hour, by the rotation of the 
earth from west to east. 

Rule. Find the number of miles contained in 
a degree of longitude in the latitude of the given 
place, which multiply by 15 for the distance re- 
quired.* 

Illus^ The earth revolves 360°, or its whole circum* 
ference, in 24 hours ; and 360°, divided by 24 hours, gives 
a movement of 15° an hour : hence the number of miles 
contained in a degree of longitude, being multiplied by 
15, will produce the number of miles that any given 
place moves in an hour. 

1 . At what rate an hour are the inhabitants of 
New-York carried by the earth's rotation on its 
axis ? 

2. Required the number of geographical, and 
English miles, the inhabitants of the following 
places are carried in an hour, by the earth's rota- 
tion on its axis ; 

Aleppo, Batavia, 

Morocco, Cape Horn, 

Cape Farewell, Cape of G. Hope, 

Nootka Sound, St. Petersburg, 

* A table showing the number of miles contained in a degree of longi- 
tude in the latitude of any place, may be found in the fore part of the book. 



GRAMMAR OF ASTRONOMY. 85 

New-Orleans, Buenos Ay res, 

Spitzbergen, Delhi. 

London, Athens, 

Philadelphia, Savannah. 



The month, day, and hour of the day, given, to 
find where the sun is vertical at that instant. 

Rule. After finding the sun's declination for 
the given time, and rectifying the globe for that 
place, bring the given place to t je *rass meridian, 
and set the index of the hour circ e at the upper 
12 ; if the given time be before noon, turn the 
globe westward as many hours as it wants of noon. 
If the given time be past noon, turn the globe east- 
ward as many hours as the time is past noon ; and 
the place exactly under the degree of the sun's 
declination, will be the place required. 

1. At 4 o'clock in the evening at London, on 
the 25th of April, where is the sun vertical ? 
Arts. The sim being in 13° northern declination, the 
north pole must be elevated 13° above the horizon, 
and as the given time is 4 o'clock in the evening-, 
the globe must be turned 4 hoirrs eastward ; the sun 
will then be vertical at Barbadoes. 

2. At 10 o'clock in the morning at New- York, 
on the 14th of Ap il, where is the sun vertical ? 

3. Where is the sun vertical, when it is 4 o'clock 
at New- York, on the 4th of July 1 

4. When it is 4 o'clock in the morning at Lon- 
don, on the 18th of August, where is the sun ver- 
tical ? 

5. When it is 1 1 o'clock in the morning at Cal- 

H 2 



5 6 tfllAMMAR OF AS¥&ON€»aiY. 

cutta, on the 1 1th of April, where is the sun veiv 
tical ? 

6. When it is 3 o'clock in the evening at Lon- 
don, on the 5th of January , where is the sun ver- 
tical ? 

7. When it is ten minutes after 5 o'clock in 
the evening at Philadelphia, on the 10th of May, 
where is the sun vertical ? 



f&oblehe zacxx. 

To find the sun's declination and the day of the 
month, by having the length of the day at any 
jplace given* 

Rule. After bringing the given place to the 
brass meridian, and setting the index of the hour 
circle at the upper 12, turn the globe on its axis 
eastward, until the index shall have passed over 
as many hours as are equal to half the number of 
hours in the given day ; elevate or depress the pole 
until the place is level with the eastern semicircle 
of the horizon, and the distance of the elevated pole 
from the horizon, will be the sun's declination. 
Turn the globe on its axis, and observe what two 
points of the ecliptic pass under the sun's declina- 
tion ; find these points in the circle of signs on the 
horizon, and exactly against them, in the circle of 
months, are the days of the month required. 

1 . Required the sun's declination, and those two 
days in the year which are each 16 hours long at 
London. 

k Am. The sun's declination is about 21° north. The 
days are the 24th of May, and the 17th of July. 



<±RAM&lAft OS* ASTR6N&MY. 8? 

1« Required the sun's declination, and those 
days of the year which are each 13 hours long at 
New-York. 

3. On what two days of the year does the sun 
set at half past 7 o'clock at Edinburgh. 

4. What two days in the year are each 14 hours 
long at Quebec ; and what is the sun's declination ? 

5. Required the sun's declination, and those 
two days which are each 1 1 hours long at Boston. 

6. Required the sun's declination, and those two 
days in the year which are each 14 hours long at 
Portland. 

7- Required the sun's declination, and those two 
days which are each i6 hours long at St. Peters- 
burg. 

8. Required the sun's declination, and those 
two days which are each 11 hours long at Phila- 
delphia. 



F&OB&Enx xxnx. 

To find the sun J s amplitude at any given place* 

Rule. Rectify the globe for the latitude of the 
place ; find the sun's place in the ecliptic, and 
bring it to the eastern semicircle of the horizon, 
and the number of degrees from the sun's place to 
the east point of the horizon, will be the sun's rising 
amplitude. Bring the sun's place in the ecliptic 
to the western semicircle of the horizon, and the 
number of degrees from the sun's place to the 
western point of the horizon, will be the sun's set- 
ting amplitude. 



$$ GRAMMAR OF ASTRONOMY. 

1. Required the sun's rising and setting ampli- 
tude at Washington, on the fourth of July. 

2 Required the sun's rising and setting ampli- 
tude at New-York, on the 16th of September. 

3. Required the sun's rising and setting ampli- 
tude at Vienna, on the 20th of August. 

4. Required in what point of the compasses the 
sun rises and sets at the mouth of Oregon, or 
Columbia river, on the 22d of May 

5. Required the sun's rising and sett'ng ampli- 
tude at the Cape of Good Hope, on the 10th of 
June. 

6 Required in what point of the compasses the 
sun rises and sets at St. Salvador, on the i4th of 
October. 

7. Required the sun's rising and setting ampli- 
tude at Boston, on the 15th of December. 

8. Required the sun's rising and setting ampli- 
tude at Archangel, on the 1 8th of January, Am- 
sterdam, on the '20th of February, Paris, on the 
24th of March, and Madrid, on the 25th of April. 



V&OBKEIK XXXV. 

Given the length of the longest day, to find the la- 
titude of a place not within the polar circles. 

Rule. If the place be in north latitude, bring 
the first point of Cancer, and if in south latitude, 
the first point of Capricorn, to the brass meridian; 
set the index of the hour circle at the upper i2 ; 
turn the globe on its axis westward, until the index 
shall have passed half as many hours as are equal 
to the length of the given day ; elevate or depress 



GRAMMAR OF ASTRONOMY. 89 

the pole, until the sun's place, Cancer or Capri- 
corn, is brought to the north point of the horizon^ 
and the elevation of the pole will show the latitude 
required.* 

1. In what degree of south latitude is the long- 
est day 14 hours? 

2. In what degree of south latitude is the long- 
est day 13 hours? 

3. In what degree of north latitude is the long- 
est day 18 hours? 

4. In what degree of north latitude is the long- 
est day 1 6^ hours ? 

5. In what latitude is the night 13 hours long? 
on the 14th of December? 

6. In what latitude is the longest day 15 hours 
long? 

7* In what degree of north latitude is the 20th 
of May 1 6 hours long ? 

8. In what degree of south latitude does the sua 
rise at 7 o'clock on the 5th of April ? 



To find the length of the longest day at any given 
place in the north frigid zone. 

Rule. Bring the given place to the north point 
of the horizon ; observe its distance from the north 
pole, on the brass meridian ; mark the number of 
degrees from the equator towards the pole ; then 
turn the globe on its axis, and observe what two 
points of the ecliptic pass under the mark above ; 

* This rule will answer for any other given day, by finding the sun's 
place for Uiat day, and using it instead of Cancer and Capricorn, 



90 GRAMMAR OP ASTRONOMY. 

find these two points in the circle of signs on the 
horizon, against which, in the circle of months, are 
the days on which the longest day begins and ends. 
The longest day at the given place, begins on 
a day preceding, and ends on a day succeeding, 
the 21st of June. 

1. Required the length of the longest day at the 
north Cape, in the Island of Mageroe, in latitude 
71° 31' north. 

Arts. The place is 18J° from the pole; the longest 
day begins on the 1 4th of May, and ends on the 3Cth 
of July. — The day is therefore 77 days long, i. e. 
the sun is 77 natural days above the horizon. 

2. Required the length of the longest day in 80 
degrees north latitude. 

3. Required the length of the longest day in 
85 degrees north latitude. 

4 Required the length of the longest day in 
latitude 75 degrees north. 

5. Required the length of the longest day in 
latitude 82 degrees north. 

6. Required the length of the longest day at the 
north pole. 

7- Required the length of the longest day at 
the mouth of Macken7ie , s river. 

8. Required the length of the longest day at 
the south pole. 

Obs. 1. The above-mentioned rule is general, and 
may be applied to the south frigid zone as well as the 
north, by reading the 21st of December for the 21st of 
June. 

2. All places whose latitude is more than 66J degrees, 
are in the frigid zone ; and to those places the sun does 
not set, or is above the horizon, during several rotations 
of the earth on its axis. 

3. A table showing the length of the longest day in 
almost all latitudes, will be found in the fore part of the 
book. 



GRAMMAR OP ASTRONOMY. 9* 



PROBLEM XX7X. 

To find the sun's meridian altitude on any day 
at any given place* 

Rule. Elevate the pole as many degrees 
above the horizon as are equal to the latitude of 
the place ; find the sun's place in the ecliptic, bring 
it to the brass meridian, and the number of de- 
grees contained on the brass meridian, between 
the sun's place and the horizon, reckoning the 
nearest way, will be the altitude required, 

1. Required the sun's meridian altitude at Lon- 
don, on the 21st of June. 

Arts. 62 degrees. 

2. Required the sun's meridian altitude at New- 
York, on the 4th of September. 

3 Required the sun's meridian altitude at 
Charleston, on the 7th of July 

4. Required the sun's meridian altitude at Cape 
Horn, on the 18th of January. 

5. Required the sun's meridian altitude at Bos- 
ton, on the 18th of November. 

6 Required the sun's meridian altitude at Stock- 
holm, on the 4th of August. 

7. What is the sun's meridian altitude on the 
17th of April, at the mouth of Columbia river? 

Obs. The sun's altitude at any time, is his height in 
degrees above the horizon at that time. 

The sun's meridian altitude is his height above the 
horizon at noon. 



92 GRAMMAR OF ASTRONOMY. 



PROBLEM XXVIX. 

To find the degree of latitude, and those places in 
the north frigid zone, ichere the sun begins to 
shine constantly without setting, on any given 
day between the 2 1st of March and the 21 st of 
June. 

Rule. Find the sun's place in the ecliptic for 
the given day, bring it to the brass meridian, and 
observe his declination ; subtract the degrees of 
the sun's declination from 90, and the remainder 
will be the latitude required ; turn the globe on 
its axisj and at all places passing under this degree* 
the sun begins to shine constantly without setting 
during several revolutions. 

1. Required in what latitude, and at what 
places, the sun begins to shine without setting, on 
the 14th of May. 

Ans. The sun's declination, 18 J degrees, being sub- 
tracted from 90°, leaves 71£° for the latitude ; the 
places passing under this latitude, are North Cape 
in Lapland, Icy Cape in the southern part of Nova 
Zembla, he. 

2. Required in what latitude, and at what 
places, the sun begins to shine constantly on the 
21st of April. 

3. Required in what latitude north, and at what 
places, the sun begins to shine constantly on the 
30th of March. 

4. Required in what latitude north, and at what 
places, the sun begins to shine constantly on the 
16th of April. 

5* Required in what latitude north, and at what 



GRAMMA OF ASTRONOMY. 9 6 

places, the sun begins to shine constantly on the 
24th of May. 

6. In what latitude north, and at what places* 
does the sun begin to shine constantly on the 4th 
of June ? 

7. Required in what latitude south, and at what 
places, the sun begins to shine constantly on the 
20th of November. 

Obs. For the south frigid zone, we may take any day 
between the 23d of September and the 21st of Decem- 
ber, and proceed as above directed. 



FHOBLEXVE X3CVIXX. 

To find that part of the equation of time, which 
depends upon the obliquity of the ecliptic. 

Rule. Find the sun's place in the ecliptic, and 
bring it to the brass meridian ; count the number 
of degrees from Aries to the brass meridian on the 
ecliptic, and on the equator, and the difference 
between them, reckoning 4 minutes of time to a 
degree, is the equation of time. If the number 
of degrees on the equator, exceed those on the 
ecliptic, the sun is slower than the clock ; if the 
number of degrees on the ecliptic, exceed those 
on the equator, the sun is faster than the clock. 

1. Required the equation of time, depending on 
the obliquity of the ecliptic, on the 17th of July. 

Arts. As the degrees on the equator exceed those on 
the ecliptic 2°, the sun is 8 minutes slower than the 
clock. 

2. Required the equation of time on the Jf 8th 
of Oetober. 

I 



__ 



94 GRAMMAR OF ASTRONOMY. 

3. What is the equation of time on the 14th of 
February ? 

4. What is the equation of time on the 1 6th of 
April ? 

5. What is the equation of time on the 22d of 
May? 

6. When the sun is in 24° of Cancer, what is 
the equation of time ? 

7. On what 4 days in the year does the sun and 
clock agree in time ? 

8. Required die equation of time on the 4th of 
July. 

Note. The earth's motion on its axis being perfectly 
equable, and thereby causing" an apparent equable mo- 
tion of the starry heavens around the same axis, pro- 
duced to the poles of the heavens ; it is plain that equal 
portions of the celestial equator, pass over the meridian 
in equal parts of time, because the axis of the world is 
perpendicular to the plane of the equator. Therefore, 
if the sun kept its annual course in the celestial equator, 
it would always revolve from a meridian to the same 
meridian again in 24 hours exactly, as shown b) a well 
regulated clock. 

But as the sun moves in the eciiptic, which is oblique, 
both to the plane of the equator, and the axis of the 
world, it cannot always revolve from a meridian to the 
same meridian again in 24 equal hours ; but sometimes a 
little sooner, and at other times a little later, because 
equal portions of the ecliptic pass over ^he meridian in 
unequal parts of time, on account of its obliquity. This 
difference is the same in all latitudes. 



PB.0B&B1/I XXIX. 

Given the day and hour at any place, to find the 
sun's azimuth and altitude. 

Rule. Rectify the globe for the latitude of the 
place, and screw the quadrant of altitude on the 



GRAMMAR OF ASTRONOMY. 95 

meridian over the latitude ; find the sun's place in 
the ecliptic, bring it to the brass meridian, and set 
the index of the hour circle at the upper 12 ; then 
if the given time be before noon, turn the globe 
on its axis eastward as many hours as it wants of 
noon ; if the given time be past noon, turn the 
globe westward as many hours as it is past noon ; 
bring the graduated edge of the quadrant of alti- 
tude to agree with the sun's place, and the num- 
ber of degrees on the horizon, reckoning from 
north or south, to the graduated edge of the qua- 
drant, will show the sun's azimuth ; and the num- 
ber of degrees on the quadrant, counting from the 
horizon to the sun's place^ will be the altitude re- 
quired. 

1 . Required the sun's azimuth and altitude from 
the north, at London, on the 1st of May, at 10 
o'clock in the morning 

Ans. The azimuth from the north is 135°, or from the 
south 45°, and the altitude 47°* 

2. Required the sun's azimuth and altitude at 
New-York, on the 4th of July, at 9 o'clock in the 
morning. 

3. What is the sun's azimuth and altitude at 
Boston, on the 16th of December, at 7 o'clock in 
the evening? 

4. Required the sun's azimuth and altitude at 
Philadelphia, on the 22d of May, at 10 o'clock in 
the morning. 

5. What is the sun's altitude and azimuth at 
Vienna, on the 17th of June, at 5 o'clock in the 
evening? 

6. Required the sun's azimuth and altitude at 
Paris, on the 4th of February, at 4 o'clock in the 
evening. 

7. Required the sun's azimuth and altitude at 



JO GRAMMAR OF ASTRONOMY. 

Copenhagen, on the 7th of July, at 7 o'clock in 
the morning. 

8. Required the sun's azimuth and altitude at 
Rome, on the 15th of March, at 6 o'clock in the 
morning. 



PROBLEM XXX. 

To illustrate the seasons of the year, and the dif- 
ferent lengths of day and night. 

Rule. Rectify the globe for the sun's declina- 
tion, and the different portions of the parallels of 
latitude above the horizon, corresponding to the 
degree of the elevation, will show the length of the 
day in each respective latitude. 

1 . For the equinoxes. The sun having no de- 
clination at this time, place the two poles of the 
globe in the horizon ; and the point Aries being 
brought to the eastern edge of the horizon, the 
point Libra will be in the western edge. When 
the sun appears to be rising at the meridian of 
Libra, he appears to be setting at the meridian of 
Aries ; and by turning the globe on its axis gent- 
ly eastward, the sun will appear to move west- 
ward ; and to be setting at all places as they suc- 
cessively disappear below the easiern edge of the 
horizon, and to be rising at all places as they suc- 
cessively emerge above the western edge of the 
horizon. 

It will be noon at these places as they pass the 
upper, and midnight as they pass the lower semi- 
circle of the brass meridian. 



GRAMMAR OF ASTRONOMY. 97 

.Juring the period of the earth's rotation, every 
place on its surface is 12 hours in the dark, and 
1 2 hours in the enlightened hemisphere ; conse- 
quently the days and nights are equal all over the 
globe. The sun s meridian altitude at each place 
will equal the complement of its latitude. Thus 
the sun's meridian altitude at New-York, is 49° 20'. 

At the equator the sun will be vertical at all 
places as they pass the upper semicircle of the 
brass meridian. 

And at all places on the equator, the sun's me- 
ridian altitude is 90°; but at the poles the sun 
having no altitude, he will appear to glide along 
the horizon during the whole space of 24 hours. 
At all places in north latitude, the sun will appear 
south ; arid at all places in south latitude, he will 
appear north when on the meridian. 

2. For the summer solstice. To the inhabitants 
in north latitude, the summer solstice happens on 
the 21st of June, when the sun enters Cancer, or 
is in 23° 28' north declination Rectify the globe 
for this declination, and bring the first degree of 
Cancer to the brass meridian ; the equator will 
then be divided into two equal parts, Aries being 
in the western, and Libra in the eastern edge of 
the horizon. At this time the day is 12 hours long 
at the equator. And from the equator northward 
as far as the arctic circle, the diurnal arcs will ex- 
ceed the nocturnal arcs, i e more than one half 
of any parallel of latitude will be above the hori- 
zon ; consequently, the days are longer than the 
nights All the parallels of latitude within the 
arctic circle being above the horizon, those places 
within this circle will have constant day ; and all 
parallels within the antarctic circle being below 
the horizon, those places will have constant night. 

12 



98 GRAMMAR OF ASTRONOMY. 

By counting the number of meridians between the 
brass meridian and the horizon in any latitude, 
reckoning an hour of time to every meridian or 
15 degrees, half the length of the day will be de- 
termined ; this doubled, gives the whole length of 
the day. Thus, in 30° north latitude there are 
seven meridians above the horizon between it and 
the brass meridian ; consequently the length of 
the dav is 14 hours. The sun will be vertical af 
all places at the tropic of Cancer as they succes- 
sively pass the brass meridian. 

Any place being brought to the brass meridian, 
its distance from the horizon, reckoned on the 
brass meridian the nearest way, will equal the 
sun's meridian altitude. Thus the sun's meridian 
altitude at Philadelphia, is 73± degrees. The far- 
ther the sun apparently moves northward, the 
more daylight will be diffused over the north po- 
lar regions ; and the sun will gradually appear to 
increase in altitude at the pole until the 21st of 
June, when his height is 23^ degrees : his height 
will then gradually decrease until the 23d of Sep- 
tember; consequently the sun will be seen six 
months at the north pole. 

3. For the winter solstice. To the inhabitants 
of northern latitudes, the winter solstice takes 
place on the 21st of December, at the time the 
sun enters Capricorn, when his declination is 23° 
28' south. Rectify the globe for this declination ; 
bring the first degree of Capricorn to the brass 
meridian, and suppose the sun to be at a distance 
directly over it. As at the summer solstice, the 
days at the equator will be 1 2 hours long ; but the 
equinoctial point Aries will be in the eastern part 
of the horizon, and Libra in the western. 

All the parallels of latitude within the antarctic 



GRAMMAR OF ASTRONOMY. 99 

circle, will be entirely above the horizon ; while 
all the parallels within the arctic circle, will be 
wholly below the horizon ; the inhabitants south 
of the equator have their longest day, while those 
north of the equator have their longest night. 

The sun will be vertical at all places in the tro- 
pic of Capricorn, as they are successively brought 
to the meridian The sun's meridian altitude will 
be found to be greater in south latitude, and less 
in north latitude, contrary to the summer solstice. 
Thus the sun's meridian altitude at London will 
he 1 5° instead of 62° ; at Philadelphia 26|° instead 
of 73|°, making a difference of 47° nearly, or the 
width of the torrid zone. 

At the time the sun enters Libra, on the 23d 
of September, the south pole begins to be enlight- 
ened, and the sun will gradually increase in altitude 
until the 21st of December, when he is 23° 28' in 
height, and at his greatest southern declination ; 
then he gradually diminishes irr altitude and decli- 
nation until the 21st of March, when he again 
enters Aries, and appears to skim along the hori- 
zon at both poles as at first. 



To find the sun's altitude for any given time at 
any place. 

Rule. Elevate the pole to the sun's declina- 
tion, fix the quadrant in the zenith, bring the 
given place to the brass meridian, and set the index 
of the hour circle at the upper 1 2 ; then if the hour 



J 00 GRAMMAR OF ASTRONOMY. 

be in the morning, turn the globe westward, but it 
in the evening, turn it eastward, as many hours as 
the time is before or after 12 ; extend the quadrant 
of altitude over the given place, and the degree 
on the quadrant over the place, will be the sun's 
altitude required. 

1. Required the sun's altitude at Washington 
on the 21st of June, at 3 o'clock in the evening. 

Arts. 51 J degrees. 

2. Required the sun's altitude at New York, on 
the 30th of April, at 10 o'clock in the morning. 

3. Required the sun's altitude at London, on 
the 17th of July, at 4 o'clock in the evening. 

4. Required the sun's altitude at Edinburgh 
on the l^th of September, at 9 o'clock in the 
morninsr. 



PELOSXi&M XXZXX. 

Given the day and hour, to find all those place* 
zohere the sun has the same altitude as any other 
given place. 

Rule. Find the place where the sun is verti- 
cal at the given time, by problem 21 ; ascertain 
its distance from the place given, and all those 
places that are at the same distance from it as the 
given place, will be the places required. 

1. Required all those places where the sun will 

have the same altitude as New York, on the 30th 

of April, at \ past 8 in the morning. 

Ans. The sun will be vertical at Cape Verd : Quebec* 

Moscheto Cove in Greenland, the western part of St. 



'GRAMMAR OF ASTRONOMY. 101 

Domingo, Cumberland Harbour in Cuba, St Sal- 
vador in the West Indies, he. are at the same dis- 
tance from New- York. — These will be the places 
required. 

2. Required all those places having the same 
altitude as Washington, on the 22d of May, at 4 
o'clock in the evening. 

3. Required all those places having the same 
altitude as Boston, at 10 o'clock in the morning, on 
the l4th of February. 

4. When it is noon at London, on the 20th of 
March, required those places where the sun will 
have the same altitude as London. 



Anyplace on the globe being given, to find all those 
places that are at the same distance from it as 
any other given place. 

Rule. With a pair of compasses take the ex- 
tent between both places, describe a circle having 
the first given place in the centre, and all those 
in the circumference of the circle, will be the 
places required. 

Or, place the quadrant of altitude over both 
places, so that the part marked may be on the 
first given place ; mark the degree over the other 
place, and describe a circle with the quadrant. 
When the quadrant is not long enough, extend a 
thread between the two places, and describe a cir- 
cle as above. 

1. Required all those places that are at the 
same distance from Constantinople as Paris. 



102 GRAMMAR OF ASTRONOMV. 

2. Required all those places that are at the 
same distance from Washington as New-York. 

3. Required those places having the same dis- 
tance from London as Rome. 

4. Required all those places having the same 
distance from Alexandria as Algiers. 



ipxieB&sxft xsxiv. 



Given any number of days not greater than 186^ 
in north, or 178|- south latitude, to find the lati- 
tude in which the sun does not set during the 
given time. 

Rule? In the circle on the horizon, count half 
the given number of days from the 21st of June, 
or the 22d of December, as the place may be in 
north or south latitude, eastward or westward ;* 
and ascertain the sun's declination corresponding 
to the days when the reckoning ends, by problem 
14; the same number of degrees reckoned from 
either pole, on the brass meridian, will be the la- 
titude required. 

1. Required the degree of north latitude where 
the sun continues above the horizon 134 natural 
days. 

*Qns. 67 days (half of the given number) being count- 
ed from the 21st of June eastward, will correspond 
to the 15th of April, or being counted westward to 
the 27th of August ; the sun's declination on either 
of these days being 10° north, the latitude required 
will be 80° north. 

* If the given place be in north latitude, reckon from the 21st of June 
eastward; but if it be south latitude, reckon from the 22d of December 

westward-. 



GRAMMAR OF ASTRONOMY. 103 

2. Required the latitude where the sun is 116 
days above the horizon. 

3 Required in what degree of north latitude 
the sun will be 48 days above the horizon. 

4. Required in what latitude the sun continues 
96 days above the horizon. 



To find the breadth of the several climates from 
the equator to the poles.* 

Rule. For the northern hemisphere, elevate 
the north pole 23^ 28 above the horizon, bring 
the first degree of Cancer to the meridian, and 
set the index of the hour circle at 12; turn the 
globe on its axis easrward until the index shall 
have passed ovet \ of an hour ; then mark with a 
lead pencil, that point of the meridian passing 
through I abra, and intersected by the horizon ; 
continue this rotation of the globe until the index 
shall have passed over another quarter of an hour, 
and mark as before, and so on until the meridian 
passing through Libra, will no longer intersect the 
horizon ; bring these marks severally to the brass 
meridian, and they will show the latitudes where 
each climate ends, from the equator to the arctic 
circle ; their difference will be the breadth between 
them severally. 

For the climates within the polar circles, as- 
certain the latitude answering to the length of the 
longest day in each climate, for one month, two 
months, &c. which will be the latitude where all 

* A table showing- the breadth of ihe several climatei may be found at 

page 54. 



104 GRAMMAR OF ASTRONOMY. 

the climates severally end ; the difference of which 
will be the breadth of each climate. 

1. Required the breadth of the 6th climate. 
Ans. Extent, from 36° 31' to 41° 24' north— Breadth 

4° 59'. 

2. Required the breadth of all the climates se- 
verally. 

Obs. On Adam's and Cary's globes the above-men- 
tioned marks are not necessary, as the meridian passing 
through Libra, is divided into degrees the same as the 
brass meridian ; and the horizon will intersect this me- 
ridian in the several degrees corresponding to the end 
of each climate. 



PROBERS xxxvx. 

To represent the natural position of the earth by 
placing the globe in the sunshine. 

Rule. With the mariner's compass, (allowing 
for variation if any,) place the globe due north and 
south, bring the place in which you are to the 
meridian, and elevate the pole to the latitudes ; 
the globe will then agree in every respect with the 
situation of the earth itself at that time. — All the 
circles of the globe, will correspond with the same 
imaginary circles in the heavens ; and every king- 
dom, state, and town laid down on the globe, will 
have the same relative situations as the real ones, 
which they represent on the surface of the earth. 



GRAMMAR OF ASTRONOMY. 105 



pmos£rm XZXVXI. 

The latitude, sun's place, and altitude being given, 
to find the sun's azimuth, and the hour of the 
day. 

Rule. After having rectified the globe for 
the latitude, zenith, and sun's place, and set the 
index of the hour circle at 12, turn the globe east- 
ward or westward, according as the sun's altitude 
may be given in the forenoon or afternoon, until 
the sun's place agrees with the given degree of 
altitude on the quadrant ; the hours passed over 
by the index, will then show the time from noon, 
and the quadrant will point out the azimuth on 
the horizon. 

1. When the sun's altitude at New- York, on 
the morning of the 21st of June, is 30 degrees, re- 
quired the hour of the day, and the sun's azimuth. 

Ans. 7 hours 20 minutes from noon, — azimuth 83£ 
from the north towards the east. 

2. When the sun's altitude at London, on the 
afternoon of the 22d of May, is 35 degrees^ re- 
quired the hour of the day, and the sun's azimuth. 

3. At Boston, when the sun's altitude on the 
17th of August, is 40 degrees, required his azi- 
muth, and the hour of the day. 

4. On the 4th of July when the sun's altitude 
at Washington in the morning is 42°, required the 
hour of the day, and the sun's azimuth. 

Obs. If the sun's altitude be given in the morningj 
turn the globe eastward, if in the evening, westward, 



i 0(> GRAMMAR OF ASTRONOMY. 



PROBLEM XXXVIII. 

Given the latitude of the place, and day of the 
mouthy to find when the sun is due east and west* 

Rule. Rectify the globe for the latitude, ze- 
nith, and sun's place ; after setting the index at 
12, move the quadrant until the mark is brought 
to the east point of the horizon ; keep the quad- 
rant in this position, turn the globe on its axis 
until the sun's place is brought to the graduated 

' of the quadrant, and the hours passed over 
by the index, will be the time from noon when the 
sun is due east, and at the same time from noon 
he will be due west. 

1 . Required the hour when the sun is due east or 
west, on the 21st of June, in latitude 40° 43'. 

Ans, At about 41 minutes past 8 in the morning, the 
sun is due east, and at about 19 minutes past 3 in 
the afternoon, the sun is due west. 

2. On the 19th of May at London, at what 
hours will the sun be due east or west ? 

3. At what hours will the sun be due east and 
west at New- York, on the 20th of August ? 

4. On the 16th of December at Washington, at 
what hours will the sun be due east and west ? 



PROBLEM XXXIX. 

Given the day and hour when a solar eclipse will 
happen, to find where it will be visible. 

Rule. Ascertain the place where the sun will 
be vertical at the given hour, by problem 21 : and 



GRAMMAR OF ASTRONOMY. 107 

at ail places within about 35° of the place where 
the sun is vertical, the eclipse may be visible, par- 
ticularly if it be a total eclipse. 

1. There being an eclipse of the sun observed 
at Greenwich on the 3d of March, beginning 17 ni. 
past noon, middle 46m. past 1, and ending 9m. 
past 3 ; required those places where the eclipse 
will be visible.* 

Am. In all of Europe, and a great portion of Ameri- 
ca, Asia, and Africa. The eclipse will be annular 
along the central track of the penumbra as in Ice- 
land, at their 12 o'clock. As the sun's apparent 
diameter exceeded the moon's, at that time, it will 
be no where a total eclipse. 



VRCBIiSBS ra. 

Given the day and hour when a lunar eclipse will 
happen, to find all those places on the globe 
» where it will be visible at that time. 

Rule. Ascertain the sun's place for the given 
time, elevate the pole farthest from the sun's place, 
to the observed degree of declination ; bring the 
place where the hour is given to the brass meri- 
dian, and set the index at 12 ; if the given time 
be in the morning, turn the globe westward, but if 
in the afternoon, turn it eastward, as many hours 
as the time is before or after noon ; and the people 
precisely under the sun's declination, will be the 
antipodes of the people where the moon is eclipsed 
vertically. Keep the globe in this position, and 
set the index again at 12, then turn it until the 
index shall have passed over 12 hours ; and at all 

* For more examples, see table of eclipses, page 47. 



10S GRAMMAR OP ASTRONOMY. 

those places above the horizon, the eclipse will be 
visible ; at those places along the western edge of 
the horizon, the eclipsed moon will be rising ; at 
those along the eastern, it will be setting ; and at 
the place precisely under the zenith, it will be 
eclipsed vertically. 

1. At New- York, on the 10th of March, the be- 
ginning of a lunar eclipse being 13m. past 12 at 
night, and the end 48m. past 2 in the morning, 
apparent time, required those places where it will 
be visible.* 

Ans. The sun is found to be in about 4J° south de- 
clination; the north pole must be elevated to this 
declination, and New-York brought to the meri- 
dian; let 1 1 hours 47 minutes, the time before noon, 
be taken, and the problem performed according to 
the rule, and the eclipse will be found visible in all 
America, the greater part of Europe, and a part of 
Africa. 

Obs. Lunar Eclipses continuing for a considerable 
time, may be visible in more than one hemisphere of the 
earth, during the eclipse. This is owing to the motion 
of the earth on its axis. 

Concluding remarks on the Terrestrial Globe* 

1. The latitude of any place is equal to the elevation 
of the pole above the horizon of that place, and the ele- 
vation of the equator is equal to the complement of the 
latitude. 

2. Those places which lie on the equator, have no la- 
titude, it being there that latitude begins ; and those 
places which lie on the first meridian, have no longitude, 
it being there that longitude begins. Consequently that 
particular place of the earth, where the first meridian 
intersects the equator, has neither latitude nor longi- 
tude. 

3. At all places of the earth except the poles, all the 
points of the compass may be distinguished in the hori- 

* For more examples see table p. 47. 



GRAMMAR OF ASTRONOMY. 109 

zon ; but from the north pole every place is considered 
south ; and from the south pole every place is consi- 
dered north. Hence as the sun is constantly above the 
horizon of each pole for half a year in its turn, he cannot 
be said to depart from the meridian of either pole, for 
half a year together. Consequently, at the north pole 
it may be said to be noon every moment for half a year ; 
and let the winds blow from what part they may, they 
must always blow from the south ; and at the south pole 
they must always blow from the north 

4. As one half of the ecliptic is above the horizon of 
the poJe, and the sun, moon 7 and planets, move nearly 
in the ecliptic, they will all rise and set at the poles. 
But, because the stars never change their declinations 
from the equator, (at least not sensibly in any ag-e,) those 
which are once above the horizon of either pole, never 
set below it, and those which are once below it never 
rise. 

5. Every place of the earth equally enjoys the benefit 
of the sun, in respect of time, and are equally deprived 
of it. 

6. All places upon the equator have their days and 
nights equally long", i. e. 12 hours each, at all times of 
the year For although the sun declines, alternately 
from the equator towards the north and south- yet, as the 
horizon of the equator cuts all the parallels of latitude 
and declination into halves, the sun must always continue 
above the horizon for one half of a diurnal revolution 
about the earth, and for the other half below it. 

7. When the sun's declination is greater than the la- 
titude of any place, upon either side of the equator, the 
sun will come twice to the same azimuth or point of the 
compass in the forenoon, at that place, and twice to a 
like azimuth in the afternoon ; that is, he will go twice 
back every day, while his declination continues to be 
greater than the latitude. Thus, supposing the globe to 
be rectified to the latitude of Barbadoes, which is 13 de- 
grees north, and the sun to be any where in the eclip- 
tic, between the middle of Taurus and the middle of 
Leo; if the quadrant of altitude be set at about 18 de- 
grees north of the east in the horizon, the sun's place be , 
marked with a lead pencil upon the ecliptic, and the 
globe be then turned westward on its axis, the said mark 

K2 



110 GRAMMAR OF ASTRONOMY. 

will rise in the horizon a little to the north of the quad- 
rant, and thence ascending*, it will cross the quadrant 
towards the south ; but before it arrives at the meridian, 
it will cross the quadrant again, and pass over the meri- 
dian northward of Barbadoes. And if the quadrant be 
set about 18 degrees north of the west, the sun's place 
will cross it twice, as it ascends from the meridian to- 
wards the horizon, in the afternoon. 

8. At all places of the earth between the equator and 
the poles, the days and nights are of equal length (12 
hours each) when the sun is in the equinoctial; for, in 
all elevations of the pole, short of 90 degrees, one half 
of the equator or equinoctial will be above the horizon, 
and the other half below it. 

9. The days and nights are never of an equal length 
at any place between the equator and polar circles, but 
when the sun enters the signs Aries and Libra. For, in 
every other part of the ecliptic, the circle of the sun's 
daily motion is divided into two unequal parts by the 
horizon. 

10. The nearer a place is to the equator, the less is 
the difference between the length of the days and nights 
in that place ; and the more remote, the contrary. The 
circles which the sun describes in the heavens, every 24 
hours, being cut more nearly equal in the former case, 
and more unequally in the latter. 

11. At all places lying upon any given parallel of lati- 
tude, however long or short the day or night be at any 
one of these places, at any time of the year, it is then of 
the same length at all the rest ; for, in turning the globe 
on its axis, when rectified according to the sun's decli- 
nation, all these places will be equally long above or 
below the horizon. 

12. The sun is vertical twice a year to every place 
between the tropics ; to those under the tropics, once a 
year, but never any where else. For there can be no 
place between the tropics, but that there will be two 
points in the ecliptic, whose declination from the equator 
is equal to the latitude of that place ; and but one point 
of the ecliptic which has a declination equal to the lati- 
tude of places on the tropic, which that point of the eclip- 
tic touches ; and as the sun never goes without the tro- 
pics, he can never be vertical to any place that lies 
without them. 



GRAMMAR OF ASTRONOMY. Ill 

13. At all places in the torrid zone, the duration of 
the twilight is less, because the sun's daily motion is 
more perpendicular to the horizon. In the frigid zones, 
greater ; because the sun's daily motion is nearly paral- 
lel to the horizon; and therefore he is the longer in 
passing 18 degrees below it, until which time the twi- 
light always continues. And in the temperate zones, it 
is at a meridian between the two, because the obliquity 
of the sun's daily motion is so. 

14. At all places lying exactly under the polar circles, 
the sun, when he is in the nearest tropic, continues 24 
hours above the horizon without setting; because no 
part of that tropic is below their horizon. And when 
the sun is in the farthest tropic, he is for the same length 
of time without rising, because no part of that tropic is 
above their horizon. But at ail other times of the year ; 
he rises and sets there, as in other places, because all 
the circles that can be drawn parallel to the equator, 
between the tropics, are more or less cur by the horizon, 
as they are farther from, or nearer to that tropic which 
is all above the horizon ; and when the sun is not in 
either of the tropics, his diurnal course must be in one 
of these circles. 

15. At all places in the northern hemisphere, from 
the equator to the polar circles, the longer day and 
shorter night is when the sun is in-the northern tropic ; 
and the shorter day and longer night is when the sun 
is in the southern tropic ; because no circle of the sun's 
daily motion is so much above the horizon, and so little 
below it, as the northern tropic ; and none so little above 
it, and so much below it, as the southern. la the south- 
ern hemisphere, the contrary. 

16. At all places between the polar circles and poles, 
the sun appears for some number of days, or rather 
some number of diurnal revolutions, without setting: 
and at the opposite time of the year, without rising ; be- 
cause some parts of the ecliptic never set in the former 
case, and as much of the opposite never rise in the lat- 
ter. And the nearer, or the more remote from the pole, 
these places are, the longer or shorter is the continu- 
ance of the sun's presence or absence. 

17. If a ship sets out from any port, and sails round 
the earth eastward to the same port again. let her oc- 






112 GRAMMAR OF ASTRONOMY. 

cupy what time she may on the vojage, the sailors in 
reckoning their time, will gain one complete day at 
their return, or count one day more than those who re- 
side at the same port ; because by going contrary to the 
sun's diurnal motion and being more forward every eve- 
ning than they were in the morning, their horizon will 
get sooner above the setting sun, than if they had been 
for a whole day at the same place. And thus, by cutting 
off a part proportionable to their own motion, from the 
length of every day, they will gain a complete da\ of 
that sort at their return, without absolutely gaining one 
moment of time more than is elapsed during their course, 
to the people of the port. If they sail westward, they 
will reckon one da>- less than if they had remained at 
the port, because by gradually following the apparent 
diurnal motion of the sun, ihey will keep him each par- 
ticular day so much longer above their horizon, as will 
answer to that day's course; and by that means, they 
will cut off a whole day in reckoning at their return, 
without absolutely losing one moment of time. 

Hence, if two ships should set out at the same time 
from any port, and sail round the globe, one eastward and 
the other westward, so as to meet at the same port on 
any other day whatever, they will differ two days in 
reckoning their time at their return. If they sail twice 
round the earth, they will diiTer four days.&c, making 
two days difference each time. 



#f trie ®tumm mm 



1 . Tn treating of the celestial globe, it may be observed, 
that as the equator, ecliptic, tropics, polar circles, hori- 
zon, and brass meridian, are exactly alike on both globes, 
all the former problems concerning the sun, rectifying 
the globe, &c, are performed in the same way by both 
globes. 

2. The latitude and longitude of the stars, and other 
celestial bodies, are not reckoned as they are on the ter- 
restrial globe ; for all terrestrial latitudes are reckoned 
from the equator, and longitudes from the meridian, of 
some remarkable place, as, London by the English, 
Pans by the French, Washington by the citizens of the 
Uiiited States, &c, But the astronomers of ail nations 
agree in reckoning the latitude of the celestial bodies 
from the ecliptic ; and their longitude from the equinoc- 
tial colure, where it cuts the beginning of Aries °f , east- 
ward, quite round the globe to the same point again. 
Consequently those stars which lie between the equi- 
noctial and the northern half of the ecliptic, have north 
declination and south latitude; those lying between the 
equinoctial and the southern half of the ecliptic, have 
south declination and north latitude ; and all those lying 
between the tropics and poles, have their declination 
and latitudes of the same denomination. 

3. There are six great circles on the celestial globe, 
which cut the ecliptic perpendicularly, and meet in two 
opposite points in the polar circles ; which points are 
each 90 degrees from the ecliptic, and are called its 
poles. These polar points divide those circles into 12 
semicircles ; which cut the ecliptic at the beginning of 
the \% signs. They resemble so many meridians on the 



i 14 GRAMMAR OF ASTRONOMY. 

terrestrial globe, and as all places lying under any par 
ticular meridian semicircle on that globe, have the samel 
longitude, so all those points of the heavens, through 
which any one of the above semicircles are drawn, have 
the same longitude. And as the greatest latitudes on I 
the earth, are at the north and south poles of the earth, 
so the greatest latitude in the heavens, are at the north 
and south poles of the ecliptic. 

4. In order to distinguish these stars, with regard to 
their situations and positions in the heavens, the ancients 
divided the whole visible firmament of stars into particu- 
lar systems, which they called constellations; and digest- 
ed them into the forms of such animals as are delineated 
upon the celestial globe. And those stars which lie be- 
tween the figures of ihose imaginary animals, and could 
not be brought within the compass of any of them, were 
called unformed stai*s. 

5. Because the moon and all the planets were ob- 
served to move in circles or orbits which cross the eclip- 
tic, or line of the sun's path, at small angles, and to be 
on the north side of the ecliptic for one half of their 
course round the heaven of stars, and on the south side 
of it for the other half, but never to go quite 8 degrees 
from it on either side, the ancients distinguished that 
space by two small circles, parallel to the ecliptic, one 
on either side, at 8 degrees distance from it. 

6. And the space included between these circles, 
they called the zodiac, because most of the 12 constella- 
tions placed therein, resemble some living creature. 

7. It may here be observed, that in the infancy of 
astronomy, these 12 constellations stood at, or near the 
places of the ecliptic, where the above characters are 
marked on the globe ; but now each constellation has 
advanced a whole sign, on account of the recession of 
the equinoctial points from their former places. Thus 
the constellation Aries is now in the former place of 
Taurus, Taurus in the former place of Gemini, and 
so on. 

8. The stars appear of different magnitudes to the 
eye ; probably because they are at different distances 
from us. Some of the most remarkable have names 
given them, as Castor and Pollux in the head of the 



GRAMMAR OF ASTRONOMY 



115 



2\oins, Sirius in the mouth of the Great Dog, Procyon 
ra the side of the Little Dog, ^returns in Bootes, foe. 

Having" premised these observations, we shall endea- 
vour to introduce alt the most useful problems to be 
performed by the learner, together with an alphabetical 
tfst of the constellations, showing- the right ascension and 
declination of the middle of each, that they may the 
more readily be pointed out on the globe. 



Alphabetical List of the Constellations. 



i 
12 

>? 

4 
t5 

5 
|0 
31 
30 
20 
%9 

I 
!3 
27 
23 
14 

9 
£5 



Andromeda. N. . . . . . 

Antinous. N 

Apus, vel Avis Indica. S. . . 

Aquarius. Z. 

Aquila. N 

Ara. S 

Aries. Z. 

Argo Navis. S. 

Asterion et Chara. N. . . . 

Auriga. N 

Bootes. N. ...... 

Srandenburgium Sceptrum. S. 
Cameleopardalus. N. . . . 

Cancer. Z 

Canis Major. S 

Canis Minor. S 

Capricornus. Z 

Caput Medusae. N. . . . 

Cassiopeia. N 

Centaurus. S. ..... 

Cepheus. N 

Cetus. S , 

Cerberus. N 

Chamoeleon. S. • ... 

Circinus. S 

Columba Noachi. S. . . . 
Coma Berenices. N, . . . 
Cor Caroli. N 



High. 
Ascen. 

14 

292 
252 
3:35 
295 
55 
30 

200 

75 

212 

67 

68 

128 

105' 

120 

310 

44 

12 

200 

338 

25 

271 

175 

222 

85 

185 

191 



Declin. 

34 N. 


75 S. 

4 S. 
8 N. 

55 S. 
22 N. 
50 S. 
40 N. 
45 N. 
20 N. 
IS S. 
70 N. 
20 N. 
20 S. 

5 N. 
20 S. 
40 N. 
60 N. 
50 S. 
65 N. 
12 S. 
22 N. 
78 S, 
64 S. 

35 S, 
26 N. 
39 N. 



116 



GRAMMAR OF ASTRONOMY. 



30 

12 

19 

18 

25 

27 

17 

44 

26 

7 

43 

2 

II 

3 

32 

13 

37 

6 

39 

31 

28 

5 

8 

13 

7 

21 

34 

1 14 

17 

|. 8 

4 

1 

4J 

.22 

26 

22 

35 

10 

3 

33 

18 



Corona Australis. S. . . . 
Corona Borealis. N. . . . 

Corvus. S 

Crater. S 

Crux. S 

Cyg-nus. N 

Delphinus. N 

Dorado or Xiphias.S. . . . 

Draco. N 

Equulus. N 

Equuleus Pictorius. S. . • 

Endanus. S 

Fornax Chymica. S. . . , 

Gemini. Z 

Grus. S 

Hercules. N 

Horolog-ium. S. .... 

Hydra. S 

Hidrus. S 

Indus. S 

Lacerta. N 

Leo Major. Z. ..... . 

Leo Minor. N 

Lepus. S 

Libra. Z 

Lupus. S 

Lynx. N 

Lyra. N 

Machina Pneumatica. S. 

Microscopium S 

Monoceros. S 

Mons Maenalus. N. ... 

Mons Mensae. S 

Musca N 

Musca Australis, vel Apis. S. 
Norma, vel Quadra Euclidis. S. 
Octans Hadleianus. S. . . 
Officina Sculptoria. S. . . 

Orion. S 

Pavo. S . . 

Pegasus N. ..... . 



Asrcn. 

278 
235 
185 
168 
183 
3 ■ 
308 



270 

316 

84 

bO 

42 

i ii 

330 

255 

40 

139 

28 

315 

33 

150 

150 

80 

220 

230 

ill 

283 

150 

315 

110 

225 

76 

40 

;85 

242 

310 

80 
302 
340 



GRAMMAR OF ASYRO'KOMY. 



117 



31 

36 

12 

9 

46 

4-2 

16 

38 

47 

9 

16 

7 

8 

5 

2 

3 

2 

4 

29 

40 

20 

24 

21 

24 

23 

6 

15 

44 



Perseus. N. ..-•••• . 

Phoenix. S 

Pisces. Z 

Piscis Notus, vel Australis. S. . 

Piscis Volans. S 

Praxiteles, vel Cela Sculptoria.S. 

Pyxis Nautica. S 

Reticulus Rhomboid alis. S. . . 

Robur Caroli. S 

Sagittarius. Z 

Sagitta. N 

Sextans. S 

Scorpio. Z 

Scutum Sohieski. N. . , . . 

Serpens. N. . 

Serpentarius. S 

Taurus. Z 

Taurus Poniatowski. N. . . . 
Telescopium. S. . . . . . 

Toucan. S. . 

Triangulum. N 

Triangulum Australe. S. . * . 
Triangulum Minus. N. ... 

Ursa Major. N 

Ursa Minor. N. . . • • 

Virgo. Z 

Vulpecula et Anser. N. . . . 
Xiphias. S 



Right 


Deeliru 


46 


49 N. 


10 


50 S. 


5 


10 N. 


335 


30 S. 


127 


68 S. 


68 


40 S. 


130 


30 S. 


62 


26 S. 


159 


50 S. 


285 


35 S. 


295 


18 N. 


5 





244 


26 S. 


275 


10 S. 


235 


10 N. 


260 


13 N. 


65 


61 N. 


275 


7 N. 


278 


50 S. 


359 


66 S. 


27 


32 N. 


238 


65 S. 


32 


28 N. 


153 


60 N. 


235 


75 N. 


195 


5 N. 


300 


25 N. 


75 


62 S. 



Note. The figures in the left hand column point to 
the numbers in the foregoing table where the English 
name is given, 



118 GRAMMAR OF ASTRONOMY. 

Problems performed by the Celestial Globe, 

PB.OBZ.EM Z. 

To find the latitude and longitude of a star. 

Rule. Bring the pole of the ecliptic to the 
brass meridian ; place the upper end of the quad- 
rant of altitude over that pole of the ecliptic near- 
est the star ; move the other end of the quadrant 
until its graduated edge is brought to the star; 
then the number of degrees on the quadrant be- 
tween the ecliptic and the star, is its latitude ; and 
the number of degrees on the ecliptic between the 
first degree of Aries and the quadrant, reckoning 
according to the signs eastward, is its longitude. 

1. Required the latitude and longitude of Alde- 
baraa in the eye of Taurus. 

Ans. 5° 28' south latitude, and 2 signs 6° 53' longitude. 

2. Required the latitude and longitude of 

Arcturus in Bootes, 

Pollux in Gemini, 

Procyon in Canis Minor, 

Argol in Perseus, 

Rastaben in Draco. 

Vega in Lyra, 

Antares in Scorpio, 

Altair in Aquila, 

Fomalhaut in the Southern Fish, 

Markab in Pegasus, 

Deneb in Cygnus 

Obs. The longitude of the sun, a star or planet, is 
reckoned on the ecliptic from the point Aries, eastward 
quite round the globe. 



GRAMMAR OF ASTRONOMY. 119 



PHOBkBEE £1. 

To find the declination and right ascension of a 

star. 

Rule. Bring the given star to the brass meri- 
dian, and the degree above it will be its declina- 
tion ; and the number of degrees on the equinoc- 
tial between the brass meridian and the point 
Aries, will be its right ascension. 

1. Required the declination and right ascension 
of Dubhe in the back of the Great Bear. 

Am. Its declination is 62° 48' north ; and its right 
ascension 162° 49'. 

2. Required the declination and right ascension 
of Mirach in Andromeda, 

Algol in Perseus, 
Aldebaran in Taurus, 
Arcturus in Bootes, 
Procyon in the Little Dog, 
Vega in Lyra, 
Pollux in Gemini, 
Rastaben in Draco ; 
Rigel in Orion, 
Antares in Scorpio, 
Canopus in Argo Navis, 
Menkar in Cetus, 
Algorab in the Crow. 

Obs. The degree of the equinoctial thai comes to the 
meridian with the sun, planet, or star, reckoning from 
the first degree of Aries, is its right ascension. 

The distance of the sun, star, or planet, in degrees 
from the equinoctial towards either pole, north or south. 
is its declination. 



J39 feJlAJ»3lAR OF ASTRONOMY. 



PROBLEM XXX. 

^Tojind the declination and right ascension of tM 
sm or a planet on any given day in the year. 

Rule. 1. Find the sun's place in the ecliptic; 
bring it to the brass meridian, and the degree over 
it will be his declination ; and the distance in de- 
grees, from the brass meridian to the point Aries* 
will be his right ascension. 

2. For a planet. Find in the nautical almanac^ 
or some good ephemeris, the planet's geocen- 
tric place in the ecliptic for the given day, and 
mark it with a soft lead pencil on the globe ; bring 
it to the brass meridian, and the degree over it^ 
will be its declination ; and the distance from the 
brass meridian to the point Aries, will be its right 
ascension. 

1. Required the right ascension and declination 
of the sun on the 1st of January. 

2. Required the declination and right ascension 
of the sun on the 14th of February. 

3. Required the declination and right ascension 
of Venus on the 20th of March. 

4. Required the declination and right ascension 
6f Mars on the 7th of April. 

5. Required the right ascension and declination 
of the moon on the 4th of May. 

6. Required the declination and right ascension 
of Jupiter on the 1st of June. 

7. Required the declination and right ascension 
*of Saturn on the 4th of July. 

8. Required the right ascension and declination 
of Eferschel on the 16th of August. 



tiRAMMAR OF ASTRONOMY. I3T1 



WELQBliBm IV. 



Given the latitude and longitude of a sia\ 
planet, to find its place on the globe. 



or 



Rule. Place that part of the quadrant of alti- 
tude marked ? on the given longitude in the eclip- 
tic, and the upper end over the pole of the eclip- 
tic ; and under the given latitude will be found 
the star, or the planet's place required. 

1. Required that star having 6° 19' longitude, 
and 12° 36'' north latitude. 

2. When the longitude of the moon is 5 signs 
16° 8', and its latitude 2° 61' north ; required its 
place on the globe. 

3. Required those stars having the following 
latitudes and longitudes. 

Latitudes. Longitudes. 

1 16° 3' S. 2s. 25° 51' 

22 52 N. 2 18 57 

31 8 S. 4 13 56 

10 4 N. 3 17 21 

44 20 N. 7 9 22 

27 N. 4 26 67 

4. When the longitude of Mercury is Is. 19^ 
42', and its latitude 2° 20' south; required its 
place on the globe. 

5. The longitude of Venus being 2s. 12° 26', 
and the latitude nothing; required its place on 
the globe. 

6. The longitude of Mars being 10s. 7° 35% 
and its latitude 2° 59' ; required its place on the 
globe. 

7. When the longitude of Jupiter is 4s. 5° ] 9' S, 

L 2 



122 GRAMMAR OF ASTRONOMY. 

and its latitude 42' north ; required its place oil 
the globe. 

8. The longitude of Saturn being 9s. 18° 30', 
and its latitude 21' north; required its place on 
the globe. 

9. When the longitude of Herschel is 7s. 25° 
20', and its latitude 14' north; required its place 
on the globe. 



PROBLEM V. 

Given the declination and rigid ascension of a 
star or planet, to find its place on the globe. 

Rule. Bring the given degree of right ascen- 
sion to the brass meridian ; and under the given 
degree of declination will be the star, or planet's 
place required. 

1. Required that star whose declination is 52° 
27' north, and right ascension 26l° 29'. 

Ans. Aboye the left foot of Castor in the milky-way. 

2. When the moon's right ascension is 91° 3', 
and its declination 24° 48'; required its place on 
the globe. 

3. Required those stars having the following 
light ascension and declination, 

Right ascension. Declination. 



46° 


32' 


76 


14 


25 


54 


7 


19 


100 


27 


86 


13 


99 


5 



9° 


34' S. 


8 


27 S. 


19 


50 N. 


55 


26 N. 


32 


19 N. 


44 


55 N. 


16 


26 S] 



GRAMMAR 0£ ASTRONOMY. 123 

4. The declination of Venus being 11° 41' north, 
and its right ascension 31° 30' ; required its place 
on the globe. 

5. The moon's right ascension at midnight 
being 352° 21', and its declination 17° 25' south ; 
required its place on the globe. 

6. The right ascension of Jupiter being 138°, 
and its declination 10° 29' south; required its 
place on the globe. 



FROBLSSE VI. 

To fold the distance between any two given stars 
in degrees. 

Rule. Lay the quadrant of altitude over the 
two given stars; and the number of degrees be- 
tween them, reckoned on the quadrant, will be 
their distance as seen from the earth. Or, extend 
a thread over any two given stars ; apply the dis- 
tance found to the equator, and count the number 
of degrees. 

1. Required the distance between Altair in the 
Eagle, and Vega in Lyra. 

Ans. 35 degrees. ^8 

2. Required the distance between Arcturus in 
Bootes, and Procyon in the Little Dog 

3. What is the distance between Argol in Per- 
seus, and Aldebaran in Taurus ? 

4. Required the distance between Vega in Ly- 
ra, and Rastaben in Draco. 

5. What is the distance between Pollux in Ge- 
mini, and Altair in the Eagle ? 



124 GRAMMAR OF ASTRONOMY. 

6. Required the distance between Rigel in 
Orion, and Algorab in the Crow. 



PEOBLUH VII. 

Given the latitude of the place, and day of the 
month, to find the meridian altitude of any star 
or planet. 

Rule. 1. Elevate the pole as many degrees 
above the horizon, as are equal to the latitude of 
the place. 

2. For a star. Bring the given star to the brass 
meridian, and the number of degrees on the me- 
ridian between the star and the horizon, will be 
its meridian altitude. 

3. For a planet. Look in the Nautical Alma- 
nac, or an ephemeris, for the planet's right ascension 
and declination for the given day, and mark its 
place on the globe with a soft lead pencil ; bring 
the planet's place to the brass meridian, and the 
number of degrees between it and the horizon* 
will be its meridian altitude. 

1. Required the meridian altitude of Arcturus 
in Bootes at London. 

2. Required the meridian altitude of Algol in 
Perseus at Boston. 

3. What is the meridian altitude of Aldebaran 
at New-York ? 

4. Required the meridian altitude of Rastaben 
in Draco at Quebec. 

5. Required the meridian altitude of Venus at 
Washington on the 22d of May. 

6 On the 1st of May, 1824, the right ascension 
of Venus 31° 31' north; and its declination 11° 
41' north ; required the meridian altitude. 



GRAMMAR OF ASTRONOMY. ' 125 

f. Supposing on the 4th of July at Philadelphia, 
the declination of Jupiter is 19° 29' south, and its 
right ascension 238°; required its meridian altitude. 

Obs. 1 . The number of degrees that the star or planet 
is above the horizon, as observed by means of a common 
quadrant, is called its altitude. 

2. The degrees of altitude must be counted from the 
star &c. towards the pole, which is depressed below the 
horizon. 



raOB&EK VIZI. 

. % 
Given the latitude of the place, the day, and hour, to 
place the globe so as to represent the appearance 
of the heavens j and to point out the situations of 
the several stars. 

Rule. Elevate the pole as many degrees above 
the horizon as are equal to the latitude of the 
place ; find the sun's place in the ecliptic, bring it 
to the brass meridian, and set the index of the 
hour circle at 12 ; if the time be past noon, turn 
the globe westward ; if the given time be before 
noon, turn the globe eastward, until the index 
points to the given hour, and the surface of the 
globe will then represent the appearance of the 
heavens at that place. 

1. Place the globe so as to represent the ap- 
pearance of the heavens at New-York, on the 1st 
of January, at 10 o'clock in the evening. 

2. At Boston, August 14, at 8 o'clock in the 
morning. 

3. At London, on the 30th of March, at 9 
o'clock in the evening. 

4. At Oporto, on the lfth of April, at midnight. 



126 GRAMMAR OF ASTRONOMY. 

5. At St. Petersburg, on the the 30th of May, at 
6 o'clock in the evening. 

6. At Edinburgh, on the 4th of July, at 7 o'clock 
in the morning. 

7. At Washington, on the 22d of May, at 10 
o'clock in the evening. 

8. At Paris, on* the 16th of September, at 2 
o'clock in the morning. 



PROBZiEIft XX. 

Given, two stars, one on the meridian, and the other 
in the east or the west point of the horizon, to 
find the latitude of the place. 

Rule. Bring the star observed to be on the 
meridian, to the brass meridian ; elevate or de- 
press the pole until the other star comes to the 
eastern or the western point of the horizon, observ- 
ing to keep the globe from turning on its axis ; 
and the number of degrees from the elevated pole 
to the horizon, will be the latitude required. 

1. The two pointers in the Great Bear, Dubhe 
and /3, being observed to be on the meridian, 
Vega in Lyra to be rising ; required the latitude. 

Ans. 27° nof th. 

2. Arcturus in Bootes being observed to be on 
the meridian, and Altair in the Eagle ; to be rising; 
required the latitude. 



GRAMMAR OB* ASTRONOMY* Vl7 



FROBLX3ZME X. 



Given, the day of the month, to find at what hou 
any given star comes to the meridian. 



Rule. Bring the sun's place in the ecliptic to 
the brass meridian, and set the index of the hour 
circle at the upper 12; turn the globe westward 
until the given star comes to the brass meridian, 
and the number of hours passed over, will be the 
time from noon, when the star culminates. 

1. At what hour does Arcturus come to the 
meridian of London, on the 9th of February. 

Jlns. At half past 4 o'clock in the morning* 

2. Required the time at which the following 
stars come to the meridian of Washington, 

Aldebaran on the 12th of January. 
M enkar on the 5th of November. 
Antares on the 24th of February. 
Regulus on the 4th of July, 
Rastaben on the l6th of September. 
Fomalhaut on the 14th of June. 



moaLBBE XX. 

Given, the day of the month at any place, to find 
when a star or planet vjill rise, come to the meri- 
dian, and set. 

Rule. Elevate the pole as many degrees 
above the horizon, as are equal to the latitude of 
the place ; find the sun's place in the ecliptic : 



128 GRAMMAR OP ASTRONOMY. 

bring it to the meridian, and set the index of the 
hour circle at 12: turn the globe westward until 
the star or planet comes to the eastern edge of the 
horizon, and the index will point to the hour of its 
rising from noon — continue this motion of the 
globe westward until the star or planet is brought 
to the brass meridian, and the index will point to 
the hour of its culmination — let the globe be turn- 
ed westward until the star or planet's place arrives 
at the western edge of the horizon, and the index 
will show the time of the sun's setting from noon. 

1. At what time does Aldebaran rise, culminate, 
and set at New-York, on the 1st of January? 

2. Required at what time Sirius rises, comes to 
the meridian, and sets on the 4th of March, at 
Boston. 

3. Required at what time Arcturus rises, cul- 
minates, and sets at Washington city, on the 22d 
of May. 

4. Required at what time Fomalhaut rises, cul- 
minates, and sets at Vienna, on the 14th of June. 

5. The longitude of Jupiter being 7s. 26° 34'; 
and its latitude 45 minutes north ; at what time 
does it rise, culminate, and set, at London the 4th 
of July. 

6. When the longitude of Mars is 8 signs 3 de- 
grees 20 minutes and its latitude 36 minutes north ; 
required the time of its rising, culminating, and 
setting at Paris, on the 20th of September. 

7. When the longitude of Venus is 8s. 5° 55' ; 
and its latitude 1° 41' north ; at what time does it 
rise, culminate, and set, on the 9th of December, 
at Oporto. 



GRAMMAR OP ASTRONOMY. 129 



PROBLEM XXX. 

Given, the latitude of a place, to find the ampli- 
tude of any known star, its oblique ascension 
and descension, its ascensional difference, and 
the time of its continuance above the horizon. 

Rule, Rectify the globe for the latitude of the 
place, and bring the given star to the eastern edge 
of the horizon ; the number of degrees between 
the star and the east point of the horizon, will be 
its rising amplitude, and the degree on the equi- 
noctial, cut by the horizon, will be its oblique as- 
cension. Keep the globe in this position, and set 
the index of the hour circle to 12 ; turn it west 
ward, until the given star is brought to the brass 
meridian, and the number of hours passed over by 
the index, will be the star's semidiurnal arc, or half 
the time of its continuance above the horizon. 
, The degree on the equinoctial, cut by the brass 
meridian, will be the star's right ascension ; the 
difference between which and the oblique ascen- 
sion, is the ascensional difference. Continue the 
motion of the globe westward, until the star is 
brought to the western edge of the horizon, and 
find the setting amplitude and oblique descension 
as above. 

1. At New-York, required the rising and setting 

amplitude of Procyon, its oblique ascension and 

descension, diurnal arc, and ascensional difference. 

Ans. Its rising amplitude north of the east point is 

7° ; its setting amplitude north of west is 7° ; ob* 

lique ascension, 107|°; oblique descension, 117°; 

right ascension, 112°; ascensional difference, 5° ; 

and its continuance above the horizon. 12 hours 40 

minutes. 

M 



ISO GRAMMAR OF ASTRONOMY. 

2. At Washington, required the rising and set- 
ting amplitude of Aldebaran, its oblique ascension 
and descension, diurnal arc, and ascensional diffe- 
rence. 

3. At Boston, required the rising and setting 
amplitude of Arcturus, its oblique ascension and 
descension, diurnal arc, and ascensional difference. 

4. At Philadelphia, required the rising and 
setting amplitude of Sirius, its oblique ascension 
and descension, diurnal arc, and ascensional dif- 
ference. 

PROBLEM XXII. 

The latitude of the place, day of the month, and 
hour of the day, being given, to find the alti- 
tude and azimuth of any known star. 

Rule. Elevate the pole to the latitude of the 
place, screw the quadrant in the zenith, bring the 
sun's place in the ecliptic for the given day to the 
brass meridian, and set the index of the hour cir- 
cle at 12 ; if the given time be in the morning, 
turn the globe eastward, but if in the evening, turn 
it westward, as many hours as the time is be- 
fore or after noon ; keep the globe in this position,, 
move the quadrant of altitude until its graduated 
edge is brought to the centre of the given star ; 
the number of degrees on the quadrant between 
the horizon and the star, is its altitude ; and the 
degree on the horizon, cut by the quadrant, will 
be its azimuth, reckoning from north or south. 

1. When it is 5 o'clock in the morning, on the 



GRAMMAR OF ASTRONOMY. 131 

23d of September, at Philadelphia, required the 
altitude and azimuth of a, Arietis. 
Ans. Its altitude is 47°, and azimuth 78£°, from the 
south towards the west. 

2. When it is 9 o'clock in the evening at Lon- 
don, on the the 10th of February, required the al- 
titude and azimuth of Sirius. 

3 When it is 10 o'clock in the morning at 
Washington, on the 4th of July, required the alti- 
tude and azimuth of Procyon. 

4. When it is 6 o'clock in the evening at Paris, 
on the 14th of August, required the altitude and 
azimuth of Altair in the Eagle. 

5. When it is 11 o'clock in the evening at Edin- 
burgh, on the 18th of March, required the altitude 
and azimuth of Arcturus. 

6. When it is 10 o'clock in the morning, at 
Vienna, on the 17th of January, required the alti- 
tude and azimuth of Lyra in the Harp. 



hlob&eih XIV. 

To ascertain the day of the year on which any 
known star will be upon the meridian at a given 
hour. 

Rule. Bring the star to the brass meridian, 
and set the index of the hour circle at 12 ; turn 
the globe on its axis westward or eastward, accord- 
ing as the given time is in the morning or evening, 
as many hours as the time is from noon ; and the 
brass meridian will cross the ecliptic in the degree 
of the sun's place, corresponding to the time in 
the circle of months on the horizon. 



132 GRAMMAR OF ASTRONOMY. 

1. On what day of the year will Regulus in 
Leo be on the meridian of Philadelphia, at 9 
o'clock in the evening? 

Am. The time being 9 hours after noon, the globe 
must be turned eastward until the index shall have 
passed over 9 hours ; the meridian will intersect the 
ecliptic, in 15° of Aries, which will correspond to 
the 5th of April. 

2. On what day of the year will Arcturus be on 
the meridian of New-York, at 10 o'clock in the 
morning ? 

3. On what day of the year will Sirius be on 
the meridian of Washington, at 8 o'clock in the 
evening ? 

4. On what day of the year will Procyon be on 
the meridian of St. Petersburg, at 11 o'clock in 
the morning? 

5. On what day of the year will Lyra in the 
Harp be on the meridian of London, at 7 o'clock 
in the evening? 

6. On what day of the year will Altai* in the 
Eagle be on the meridian of Madrid, at 6 o'clock 
hi the morning ? 

Obs. When the time is in the morning, or before 
noon, the globe must be turned westward ; but when the 
time is after noon, it must be turned eastward. 



Given, the latitude, day of the month, and two 
stars having the same azimuth, to ascertain the 
hour of the night. 

Rule. Rectify the globe for the latitude, screw 
the quadrant of altitude in the zenith, bring the 



UftAMMAR OF ASTRONOMY. 133 

sun's place in the ecliptic to the brass meridian, 
and set the index of the hour circle at 12; turn 
the globe westward until the two stars coincide 
with the graduated edge of the quadrant of alti- 
tude, and the number of hours passed over, will 
be the time from noon. The azimuth of the given 
stars will be found on the horizon. 

1. At New-York, on the 22d of September, at 
what hour will Capella in Auriga, and Castor in 
^Gemini, have, the same azimuth, and what will 
their azimuth be at that hour ? 

Jlns. Before the stars coincide with the quadrant, the 
index will have passed over 131 hours from noon; 
consequently it will be a quarter past one ; and the 
azimuth from the north towards the east will be 63 
degrees. 

2. At London, on the 1st May, at what hour 
will Altair and Vega have the same azimuth, and 
what will be their azimuth ? 

3. At Paris, on the 20th of April, at what hour 
will Spica Virginis and Arcturus have the same 
azimuth, and what is that azimuth ? 

4. At Rome, on the 4th of July, at what hour 
will Sirius and Rigel have the same azimuth, and 
what will their azimuth be ? 



p&obkehe xvr. 

The day of the month, and the hour when a given 
star rises or sets, being given, to find the lati- 
tude of the place. 

Rule. Find the sun's place in the ecliptic for 
the given dav, bring it to the brass meridian, and 

M 2 






134 GRAMMAR OP ASTRONOMY. 

set the index of the hour circle at 12 ; turn thti 
globe on its axis eastward or westward, according 
as the given time is in the morning or evening, as 
many hours as the time is from noon ; elevate or 
depress the pole until the star is level with the ho- 
rizon, and the number of degrees that the pole is 
elevated above the horizon, will equal the latitude 
required. 

1. On the 10th of May, in what latitude does 
Altair rise at 10 o'clock in the evening ? 

Ans. 41° 35'. 

2. On the 14th of July, in what latitude does 
Dubhe in the Great Bear rise, at 8 o'clock in the 
morning? 

3. On the 20th of August, in what latitude does 
Capella rise, at 9 o'clock in the evening 1 

4. In what latitude does Acubens rise, at 4 
o'clock in the morning, on the 17th of September 1 

5. In what latitude does Antares in Scorpio rise, 
at 2 o'clock in the morning, on the 24th of No* 
vember ? 

6. In what latitude does Achernar set, at 10 
o'clock in the morning, on the 28th of December? 



FROBLBSS XVIX. 

Given, the latitude, day of the month, and two 
stars having the same altitude, to find the hour 
of the night. 

Rule. Rectify the globe for the latitude, ze- 
nith, and sun's place ; turn it on its axis westward 
until the given stars coincide with the given alti- 



GRAMMAR OF ASTRONOMi. 135 

tude on the quadrant, or until they are at the 
same distance from the horizon, if the altitudes be 
not given; the hours passed over by the index ? 
will be the time from noon, when the stars will 
have that altitude. 

1. Required the hour on the 10th of July, at 
New- York, when Castor in Gemini, and Betelguese 
in Orion, have each 5° of altitude. 

Ans. At a quarter past 4 in the morning'. % 

2. Required the hour on the 18th of January, 
at Constantinople, when Fomalhaut in the South- 
ern Fish, and Aliair in the Eagle, have each 12° 
of altitude. 

3. Required the hour on the 22d of May, at 
Boston, when Algol in Perseus, arid Aldebaran, 
have each 17° of altitude. 

H 4. Required the hour on the 31st of August, at 
'Greenwich, when a in the head of Andromeda, 
^and Menkar in Pegasus, have each 30° of altitude. 



F&OB&SMI ZVIII. 

^Given, the latitude of the place, to find the time of 
the year when any given star rises or sets cos- 
micalty) or when it rises or sets at simrising. 

Rule. Rectify the globe for the latitude, bring 
the star to the eastern semicircle of the horizon, 
and the day of the month, corresponding with the 
degree on the ecliptic, cut by the upper edge of 
the horizon, will give the time of the star's rising 
with the sun ; bring the star to the western semi- 
circle of the horizon, the sign and degree of the 
-ecliptic then intersected by the eastern edge of the 



136 GRAMMAR OF ASTRONOMY, 

horizon as before, will show on the horizon the 
time when the star sets cosmically. 

1 . Required the time of the year when the Plei- 
ades rise and set cosmically in latitude 37° north. 

Ans. They rise with the sun on the 11th of May, 
and set at the time of sunrising on the 21st of No- 
vember. 

2. Required the time of the year when Regulus 
rises and sets cosmically at New-York. 

3. Required the time of the year when Procyon 
rises and sets cosmically at London. 

4. Required the time of the year when Antares 
rises and sets cosmically at St. Petersburg. 

5. Required the time of the year when Vega 
rises and sets cosmically at Washington. 

6. Required the time of the year when Sirius 
rises and sets cosmically at Canton. 



PROBLEM XIX. 

To find the time of the year, when a star rises or 
sets heliacally, that is, when it first emerges from 
the solar rays in the morning, or disappears by 
falling into the solar rays in the evening. 

Rule. Elevate the pole to the latitude of the 
place, screw the quadrant of altitude in the zenith, 
turn the globe, and move the quadrant till the 
given star is found by it, to be 12° above the east- 
ern edge of the horizon, if the star is of the 1st 
magnitude; 13° if of the 2d; 14° if of the 3d, &c. 

The point of the ecliptic, intersected by the 
eastern edge of the horizon, will agree with the 
day of the month, on which the star will rise he- 
liacallv. 



GRAMMAR OF ASTRONOMY. 137 

Turn the globe westward, till the star is 
found, by the quadrant to be 12°, 13°, &c. above 
the western edge of the horizon, and the point of 
the ecliptic then intersected by the same edge of 
the horizon, will direct, as before, to the time of 
the star's setting heiiacally. 

1. Required the time of the year when Sirius 
rises and sets heiiacally, in latitude 31° 11£' north. 

Ans. On the 4th of August, and the 23d of May. 

2. Required the time of the year when Aldeba- 
ran rises and sets heiiacally at Paris. 

3. Required the time of the year when Arctu- 
rus rises and sets heiiacally at Stockholm. 

4. Required the time of the year when Menkar 
rises and sets heiiacally at Vienna* 



PRosxism xx. 

Given, the latitude of the place, to find the time of 
the year tolien any known star rises or sets 
achronicatty, i. e. when it rises or sets at sun- 
setting. 

Rule. Rectify the globe for the latitude of the 
place, bring the given star to the eastern semicir- 
cle of the horizon, and mark the point of the eclip- 
tic, that is cut by the western edge of the horizon, 
or that sets when the star rises ; the day of the 
month, corresponding with this point, will give 
the time when a star rises at sunset, or when it 
is first visible in the evening ; after which, turn 
the globe westward on its axis until the star is 
brought to the western part of the horizon, observe 
the degree on the ecliptic, cut hy the western edge 






138 GRAMMAR OP ASTRONOMY. 

of the horizon as before, and the day of the month, 
corresponding to the degree, will show the time 
when the star sets with the sun. 

1. Required the time when Arcturus rises and 
sets achronically, in latitude 37° 45' north. 

Am. The 12th degree of Aries will be at the western 
edge of the horizon, when Arcturus is in the eastern, 
which corresponds with the 1st of April, the time of 
its rising ; and the time of its setting is on the 30th 
of November. 

2. Required the time when Capella rises and 
sets achronically at New-Orleans. 

3. Required the time when Antares rises and 
sets achronically at New-York. 

4. Required the time when Aldebaran rises and 
sets achronically at London. 

5. Required the time when Acubens rises and 
sets achronically at Vienna. 

(). Required the time when Vega rises and sets 
achronically at St. Petersburg. 



pn.CEi.:2ryi xxi. 

Given, the latitude of the place, and day of the 
month, to find all those stars that rise and set 
cosmically, heliacally, and achronically. 

Rule. 1. After rectifying the globe for the la- 
titude, bring the sun's place to the eastern edge 
of the horizon, and all those stars along the east- 
ern semicircle of the horizon, will rise cosmically, 
and those along the western semicircle, will set 
cosmically. 

2. Screw the quadrant of altitude in the zenith. 

i 



GRAMMAR OF ASTRONOMY. 139 

turn the globe eastward on its axis until the 
sun's place cuts the quadrant 12° below the hori- 
zon, and all the stars of the first magnitude along 
the eastern semicircle of the horizon, will rise he- 
liacally. By turning the globe eastward until the 
sun's place intersects the quadrant in 13°, 14°, 
15°, 16°, &c, below the horizon, will be found all 
the stars of the 2d, 3d, 4th, 5th, &c. magnitudes, 
which rise heliacally on that day. Turn the globe 
westward, bring the quadrant to the western semi- 
circle of the horizon, and proceed as above, and 
you will have all those stars that set heliacally on 
that day. 

3. Bring the sun's place in the ecliptic to the 
western semicircle of the horizon ; all the stars 
along the eastern part will rise, and all along the 
western part will set achronically. 

1. Required those stars that rise and set cosmi- 
cally, heliacally, and achronically, at New-York, 
on the 4th of December. 

' dins. 1. Antares will be near the eastern semicircle 
of the korizon ; and will consequently rise cosmi- 
cally nearly ; — and Algol will set cosmically. 2, 
Arided in Cygnus will rise heliacally ; and in Ser- 
pens will set heliacally, &c. 3. Aldebaran, &c. will 
rise achronically; and Arcturus, &c, will set 
achronically. 

2. Required those stars that rise and set cosmi- 
cally at London, on the 4th of September. 

3. Required those stars that rise and set helia- 
cally at Philadelphia, on the 17th of January. 

4. Required those stars that rise and set achro- 
nically at Moscow, on the 20th of March. 

5. Required those stars that rise and set cos- 
mically, heliacally, and achronically, at Amster- 
dam, on the 16th of April 



140 GRAMMAR OF ASTRONOMY. 

6. Required those stars that rise and set cosini- 
cally, heliacally, and achronically, at Edinburgh, 
on the 24th of May. 

Obs. This problem is the reverse of the three fore- 
going. 

The achronical, cosmical, and heliacal rising and set- 
ting of stars, were terms used only by the ancient poets, 
and consequently the principal use of these four pro- 
blems is to illustrate some passages in their writings. 



FROBLSM XXII. 

Given the latitude of the place, day of the month, 
and azimuth of a known star, to find the hour of 
the night and altitude of the star. 

Rulb. Rectify the globe for the latitude of the 
place, bring the sun's place to the meridain, screw 
the quadrant of altitude in the zenith, and set the 
index of the hour circle to the upper 12 ; place the 
graduated edge of the quadrant opposite the given 
degree of azimuth on the horizon; turn the globe 
westward until the star is brought to the edge of the 
quadrant ; the number of hours passed over by the 
index, will be the time from noon ; and the number 
of degrees on the quadrant between the star and 
the horizon, will be the altitude required. 

1. Required at what time from noon, at Lon- 
don, on the 28th of December, the azimuth of 
Deneb in Leo, marked /3, is 62|- degrees from the 
south towards the west, and the star's altitude. 
JLns. In turning the globe, the index of the hour 
circle will pass over 19 h©urs and 45 minutes from 
noon ; consequently it is 45 minutes past 7 in the 
morning. The star's altitude is 32£ degrees. 



GRAMMAR 0.1? ASTRONOMY. 141 

2. At New- York, on the 21st of June, when the 
azimuth of Altair is 83°23 ' from the south towards 
the east, required the time of night and the star's 
altitude. 

Ans. It will be 9 o'clock in the evening, and the 
star's altitude will be 20° 22'. 

3. At Philadelphia, on the 23d September, the 
azimuth of Arietis being 79° from the south, re- 
quired the hour of the night, and the star's alti- 
tude. 

4. At London, on the 5th of May, the azimuth 
of Regulus, marked «, being 74 degrees from the 
south towards the west, required the hour of the 
night, and the star's altitude. 



Given, the latitude of the place, day of the month, 
and the altitude of a given star, to find the hour 
, of the night and the star's azimuth. 

Rule. Elevate the pole to the latitude, screw 
the quadrant of altitude in the zenith, bring the 
sun's place to the brass meridian, and set the in- 
dex of the hour circle at the upper 12; bring the 
quadrant of altitude to that side of the brass meri- 
dian, on which the star was situated when observed ; 
turn the globe westward until the centre of the 
star cuts the given degree of altitude on the qua- 
drant ; the hours passed over by the index, will 
be the time from noon when the star has that alti- 
titude, and the degree where the quadrant inter- 
sects the horizon, will be the azimuth required. 

1. At Philadelphia, on the 23d of September, 
the altitude of Arietis being observed to be 47°. 

N 



. i 



142 GRAMMAR OF ASTRONOMY. 

and west of the meridian; required the hour and 

the star's azimuth. 
Ans. In turning the globe westward, until the star 
intersects the quadrant west of the meridian at the 
given degree of altitude, the index will pass over 
17 hours, which will make the time 5 o'clock in the 
morning-. The azimuth from the south towards the 
west will be 79 degrees. 

2. At London, on the 28th of December, the 
altitude of Deneb being observed to be 40 degrees, 
and east of the meridian ; required the hour, and 
the star's azimuth. 

3. At Washington, on the 21st of March, the al- 
titude of Lyra being observed to be 50 degrees, 
and east of the meridian ; required the hour, and 
the star's azimuth. 



PEOBIEM XXXV. 

Having the meridian altitude of the sun, star, or 
planet given, to find the latitude of the place 
where the altitude was observed. 

Rule. Bring the given star, the place of the sun or 
planet, to the brass meridian, and mark the degree 
over it ; count from the marked degree on the 
brass meridian, northward or southward, as the 
sun, &c. may be north or south of the observer, 
as many degrees as are equal to the given meridian 
altitude ; then bring the degree where the reckon- 
ing ends to the horizon, and the elevation of the 
pole will be equal to the latitude. 

I. Required the latitude of that place where 
the sun's meridian altitude is 58° 17\ on the 17th 
of May, the sun being north of the observer. 
8 Ans. The sun's place, 26° 4tf of Taurus, being 1 



GRAMMAR OF ASTRONOMY. 143 

brought to the meridian, will be under 19° 20': 
count from this degree towards the north pole 58° 
17', and the reckoning will end at 77° 37'; depress 
the north pole until this point is brought to the ho- 
rizon, and the south pole will be elevated equal to 
the latitude, which will be 12° 23' south. 

2, On the 13th of August, 1825, Jupiter's meri- 
dian altitude being observed to be at the south- 
ward 46° 36' ; required the latitude of the place of 
observation. 

Ans. The longitude of Jupiter is 4s. 23° 31', and his 
latitude 0° 47' north, as given in the Nautical Al- 
manac ; the planet's place being brought to the me- 
ridian, the degrees and minutes over it will be 14° 
27' ; count 46° 36' from this point of the meridian 
towards the south pole, and the reckoning will end 
at 32° 9' south ; then depress the south pole until 
32° 9' is brought to the horizon, and the north pole 
will be elevated to the latitude, which will be 57° 
51' north. 

3. Being at sea, the meridian altitude of the 
star Capella north of the place of observation 
being found to be 76° 48', required the latitude of 
the ship. 

J3ns. 32° 36' north. 



PROBZAiaK sxv- 

Givcn the altitudes of two stars, at the same in- 
stant , to find the latitude of the place. 

Rule. Take a pair of compasses, fasten a black 
lead pencil in one foot, and open them to an ex- 
tent equal to the complement of the altitude of 
one star; then place one foot of the compasses in 
that star, and sweep an arc with the pencil ; then 
with one foot of the compasses in the other star, 



144 GRAMMAR OF ASTRONOMY. 

with the extent of the complement of the other 
star's altitude, describe another arc that will inter- 
sect the former; bring the point of intersection, 
(which will always be in the zenith,) to the brass 
meridian, and the degree over it will be the lati- 
tude required. 

The extent of the complements of altitude, may 
be taken from the equinoctial. 

1. The altitude of Aldebaran being observed to 
be 51° 45', and that of Castor to be 76° 40'; re- 
quired the latitude of the place. 

Solution. 51° 45' being subtracted from 90°, gives the 
complement 38° 15' — then with an extent of 384° 
taken from the equinoctial, and one foot of the divi- 
ders in the centre of Aldebaran, sweep an arc to- 
wards the north; then 90°— 76° 40'= 13° 20', with 
13° 20' in the compasses, and one foot in the centre 
of Castor, sweep another arc intersecting the 
former ; this point of intersection being brought to 
the brass meridian, will be under 42° north latitude. 

2. The altitude of Procyon in north latitude 
being observed 50°, and that of Betelguese in 
Orion to be at the same time 58°; required the 
latitude of the place. 

3. Required the latitude of the place where the 
altitude of Markab in Pegasus is 30°, and that of 
Altair in the Eagle is 65° at the same time. 

4. Being at sea, in north latitude, the altitude of 
Capella was observed to be 30°, and that of Alde- 
baran at the same time 35°; required the latitude. 



FROBJLEXVI XXVI. 

To illustrate the precession of the equinoxes. 

Rule. Elevate the north pole 90° above the 
horizon, and the equinoctial will be level with the 



GRAMMAR OF ASTRONOMY. ±4 J 

bring the pole of the ecliptic to that side 
of the brass meridian, which is numbered from the 
pole towards the equator, and mark the degree 
above it — this mark must be considered as the pole 
of the world ; the equinoctial will then represent 
the ecliptic, and the ecliptic will represent the 
equinoctial. Then turn the globe gradually on its 
axis from east to west, and the equinoctial points 
will move the same way, and describe a revolution 
around the globe in the same time that the pole 
of the world, represented by the pole of the eclip- 
tic, will describe a circle of 46° 56' in diameter 
around the pole of the ecliptic, which is represent- 
ed by the pole of the world. 

This circle will be completed in 25,791 years, 
called a Platonic year. Thus the pole of the hea- 
vens will vary its situation, or appear to move 
backward 50£ seconds every year. If from the 
above-mentioned mark on the meridian, the com- 
plement of the latitude be reckoned upwards, the 
mark where the reckoning ends, will be exactly 
over the latitude. Thus, the latitude of New- 
York will be 64° 11' on the brass meridian, reckon- 
ing from the southern point of the horizon, or 
from the equator. 

Obs. All the stars in the different constellations con- 
tinually increase in longitude ; consequently, either the 
whole starry heavens have a slow motion from west to 
east, or the equinoctial points have a slow motion from 
east to west. In the time^of Meton, a famous mathema- 
tician of Athens, who flourished about 430 years before 
Christ, the star marked /?, Arietis, in the constellation 
Aries, passed through the vernal equinox, whereas it is 
now upward of 30° to the westward of it. 



N2 



jJ¥O1tlf0CUOtt0 &VtVtiM8 

ON 

THE GLOBES. 

1. Required the latitude and longitude of New- 
York, Philadelphia, Washington, New-Orleans, 
Savannah, Pekin, Nankin, London, Edinburgh, 
Dublin, Paris, Marseilles, Lisbon, Madrid, Oporto, 
Vienna, Warsaw, Moscow, St, Petersburg, Stock- 
holm, Buenos Ayrcs, Lima, Havanna, Porto Rico, 
Archangel, Astrachan, Jerusalem, Constantinople, 
Rome, Algiers, Morocco, Tunis, Cairo, Barcelo- 
na, Liverpool, and Glasgow. 

2. Required the distance in English and geo- 
graphical miles, between Cape Verd and Cape St. 
Roque, London and New-York, Washington and 
Paris, St. Petersburg and Edinburgh, Boston and 
Charleston, Portland and Mobile, and between 
the northern extremity of Scotland and the south 
era extremity of England, the northern and south- 
ern, eastern and western extremities of England, 
Scotland, Ireland, France, Spain, Germany, Italy, 
Turkey, Russia, Prussia^ Austria, Sweden, and 
Denmark; the northern and southern, eastern and 
western extremities of Europe, Asia, Africa, Ame- 
rica, and New-Holland. 

3. Required the sun's declination at Washing- 
ton city, on the 1st of January ; 2d of February ; 
3d of March ; 4th of April ; 5th of May ; 6th of 
June; 7th of July; 8th of August; fnhofSeptem- 



*GHAMMAR- OF ASTRONOMY. 147 

ber; 10th of October; 11th of November; 12th 
of December. 

4. When it is 12 o'clock at London, what time 
is it at Boston ? Charleston ? New-Orleans ? the 
mouth of the Oregon or Columbia river ? Sand- 
wich Islands ? New Hebrides ? Botany Bay ? Ba« 
tavia? Calcutta? Alexandria? Cape St. Vincent? 

5. When it is 9 o'clock in the morning at Wash- 
ington city, what time is it at London ? 

6. At what hour does the sun make his first 
appearance at NewYork, on the 1st of January ? 
1st of February ? 1st of March? 1st of April? 1st 
of May? 1st of June? 1st of July? 1st of August? 
1st of September ? 1st of October ? 1st of Novem- 
ber 1 and 1 st of December ? 

7. At what hour does the sun set on the first 
day of every month in the year ? 

8. Required the length of the first day of every 
month in the year. 

9. Required the length of the longest day at 
Quito; New-Orfeans; London; St. Petersburg; 
Archangel ; the north pole. 

10. At what time does the sun rise and set ax 
New-York, on the 4th of July ? 

11. At what time does the sun rise and set at 
Boston, on the 14th of December ? 

12. How many miles make a degree of longi- 
tude in the latitude of New-York ? 

IS. What day of the year is of the same length 
as the 14th of August. 

14. At what hour is the sun due east at Quebec, 
on the 1st of June ? 

15. Required the equation of time depending 
on the obliquity of the ecliptic, on the 34th of Ja- 
nuary. 

16. What is the elevation of the north polar 



148 GRAMMAR OF ASTRONOMY. 

star above the horizon at New-Orleans when it is 
of the same height as the pole ? 

17. Required the sun's altitude at 4 o'clock in 
the evening at Boston, on the 22d of June. 

18. Required the length of the day at Paris, on 
the 4th of July. 

19. Required the hour on the 17th of October, 
when Arcturus is 30° above the horizon of St. 
John's, and eastward of the meridian. 

20. At what hour does the sun make his first 
appearance at Boston, on the 17th of April 7 

21. At what hour does the sun set at Washing- 
ton, on the 4th of January ? 

22. Does the sun shine over the north pole or 
the south, on the 14th of December ? 

23. Are the clocks at Washington city faster, 
or slower, than at London ? and how much ? 

24. Required the difference of latitude between 
St. Petersburg and Lima. 

25. What stars are constantly above the horizon 
at Washington city ? 

26. Are the clocks at Canton faster, or slower, 
than at Madrid ? and how much ? 

27. The longitude of a planet being 9s. 29° 2', 
and its latitude 14 minutes south, on the 20th of 
May, required whether it will rise before or after 
the sun, and how much ? 

28. When the longitude of Jupiter is 5s. 3° 41'; 
and its latitude 52 minutes north, September 30th, 
1825; required at what time it will rise, come to 
the meridian, and set at Baltimore. 

29. When the moon's longitude is 9° 21', and 
its latitude 4° 31' south ; what is its rising and set- 
ting amplitude at London ? 

30. When Arcturus rises at 8 o'clock in the 
evening, required the latitude. 



GRAMMAR OF ASTRONOMY. 14& 

31. In what latitude is the longest day 8 hours 
in length ? 

32. Required the antipodes of New- York. 

33. At what time does the morning twilight be- 
gin, and at what time does the evening twilight end, 
at Baltimore, on the 21st of June ? 

34. Required the distance between London and 
New- York in English miles. 

35. At the time of the summer solstice at Lisbon, 
at what time is the sun due east ? 

36. At what hour at London is the sun due east, 
at the time of the equinoxes ? 

37. Required those places having the same 
hour of the day as Portland. 

38. When the sun is vertical at Havanna on 
the 10th of June, where is it midnight 1 

39. How long will the sun shine without setting 
at the north pole ? 

40. Required those degrees of the ecliptic and 
equinoctial, that rise with Aldebaran at London. 

< 41. On what day of the year will Regulus come 
to the meridian at midnight ? 

42. At London the sun's altitude being observed 
to be 25° 30', when on the prime vertical, requir 
ed his declination, and the hour of the day. 

43. Required the sun's right ascension at Phila- 
delphia, at the time of the equinoxes. 

44. The sun's rising amplitude being 24° north- 
ward of the east point, on the 20th of May, re- 
quired the latitude of the place. 

45. Required the length of the day on the 14th 
of July, at Washington. 

46. Required the hour at Rome, when it is 5 
o'clock in the morning at Boston. 

4f. Required the sun's meridian altitude, and 
his azimuth at Oporto on the 14th of February 7 . 



M <gios$avi> of Srotw. 



Aberration, an apparent change of place in the fixed stars, arising 
from the motion of the earth, combined with the motion of light. 

Accelerated motion, when the real diurnal motion of a planet ex- 
ceeds its mean diurnal mottion 

Achemar, a star of the first magnitude in the constellation Erida- 
nus. 

Achronical rising and setting of a star or planet, is when it rises 
at sunset, and sets at sunset. 

Acubens, a star of the fourth magnitude, marked a, in the claw of 
Cancer. 

AdhiU a star of the sixth magnitude in the garment of Andromeda. 

Arided, a star of the second magnitude in the tail of Cygnus. 

Alderamin, a star of the third magnitude, marked a, in the shoul- 
der of Cepheus. 

Alamaach, a star of the second magnitude in the foot of Andromeda, 

Albireo, a star of the third magnitude near the head of Cygnus. 

Alcor, a small star in the tail of Ursa Major. 

Aldebaran, a star of the first magnitude in the eye of Taurus. 

Aldliafera, a star of the third magnitude in the mane of Leo. 

Algenib, a star;of the second magnitude in Perseus ; also a star 
in the wing of Pegasus. 

Algol, a star of the second magnitude in Caput Medusae. 

Algorab, a star of the third magnitude in the right wing of Corvus. 

Aches, a star of the third magnitude in Crater et Hydra. 

Alioth, a star of the third magnitude in the tail of Ursa Major. 

Almacanters, imaginary circles, which are supposed to be drawn 
parallel to the horizon. 

Alpheratz, a star of the second magnitude in tke head of Andro- 
meda. 

Alruccabah, the polar star in the tail of Ursa Minor. 

Altitude, the height of any celestial body above the horizon. 

Amphiscii, a name given to the inhabitants of the torrid zone, on 
account of their shadow's falling at one time of the year towards 
the north pole, and at another time towards the south pole. 

Amplitude, the distance of a celestial body from the east at its 
rising, or from the west at its setting. 

Analemma, a projection of the sphere on the plane of the meridian. 

Angha, a star of the third magnitude in Aquarius. 

Andromeda, a large northern constellation. 

Angle 9 the inclination of tv/o lines meeting in a point 



GRAMMAR OF ASTRONOMY. 151 

Anomaly, the distance of a planet from its aphelion, or apogee. 
Antceci, a name given to those inhabitants of the earth who live 

under the same meridian, and at equal distances from the equa- 
tor, but on opposite sides of it. 
Antarctic Circle, a small circle of the sphere, 23° 23' from th(5 

south pole, parallel to the equator. 
Antares, a brilliant star of the first magnitude, in the heart of 

Scorpio. 
Antecedentia, a motion of a celestial body, contrary to the order of 

the signs. 
Antipodes, those inhabitants of the earth who live diametrically 

opposite to each other, and walk feet to feet. 
Antiscii, a name given to those inhabitants of the earth who live 

under the same meridian, but on opposite sides of the equator, 

because at noon their shadows fall opposite each other. See 

Antoeci. 
Antlia Pneumatica, the air pump, a new southern constellation 

below Hydra. 
Aphelion, that part of a planet's orbit farthest from the sun. 
Apis, the bee, a small modern constellation in the southern hernia 

sphere. 
Apogee, that part of the moon's orbit farthest from the earth. 
Apparent conjunction of two celestial bodies, when they appear to 

us in the same degree of the zodiac. 
Apparent diameter of a celestial body, its angular diameter, as seen 

from the earth, measured with a micrometer. 
Apparent horizon, the circle that bounds our sight. 
Apsis, the aphelion or perihelium of a planet's orbit. 
Apus, the bird of paradise, a new southern constellation withi* 

the antarctic circle. 
Aquarius, the waterman, a constellation of the zodiac in the south- 
ern hemisphere. 
Aquila et Antinous, the eagle and Antinous, a large constellation 

in the northera hemisphere. 
Ara, the altar, an ancient constellation below Scorpio. 
Arc, a part of the circumference of a circle, or a curve line lying 

between two points. 
Arctic circle, a small circle of the sphere parallel to the equator, 

23° 28' from the north pole. 
Arcturus, a star of the first magnitude in Bootes. 
Argo Navis, the ship Argo, a brilliant constellation of the southern 

hemisphere. 
Allies, the ram, a constellation of the zodiac in the northern hemi- 
sphere. 
Arietis, a star of the second magnitude in the head of Aries. 
Ascending, in astronomy, a term used to denote the rising of a 

star or planet above the horizon, 
Ascending node, that part of a planet's orbit where if crosses the 

ecliptic northward. 
Ascmsion, (right.) that degree of the equator, reckoned from He 



152 GRAMMAR OF ASTRONOMY. 

point Aries, which comes to the meridian with the sun, star, 

or planet. 
Ascension, (oblique,) an arc of the equinoctial, contained between 

the first degree of Aries, aud that part of it which rises with the 

sun or star. 
Ascensional difference, the difference between the right and the 

oblique ascension. 
Ascii, a name given to the inhabitants of the torrid zone, because 

the sun is twice a year in their zenith Their bodies at these 

times will cast no shadow. 
Aspect, the situation of one heavenly body with regard to another. 
AsterisniySx. collection of stars. 
AsteriSn, the northern hound. 
Astrolabe, a stenographic projection of the sphere upon the plane 

of one of the great circles. 
Astrology, anciently synonymous with astronomy ; also a pretend- 
ed art of foretelling future events by the aspects of the stars. 
Astronomy, a science treating of the celestial bodies. 
Altair, a bright star of the first magnitude in the back of Aquila. 
Atmospliere, an elastic fluid, which surrounds the earth. 
Attraction, that power by which bodies are made to approach 

each other. 
Auriga, the wagoner, a constellation of the northern hemisphere. 
Aurora, the morning twilight, first appearing when the sun is 

about 18° below the horizon. 
Aurora Borealis, meteors appearing in the north. 
Austral, southern. 
Axis of a celestial body, an imaginary line on which it is supposed 

to revolve. 
Axis, (conjugate,) the shortest axis of an ellipse. 
Axis, (transverse,) the longest axis of an ellipse. 
Azimuth, the bearing of a heavenly body from the meridian. 
Eaten Kaitos a star of the third magnitude in Cetus. 
Bellatrix, a star of the second magnitude in the shoulder of Orion. 
Benetnach, a star of the second magnitude in the tail of Ursa 

Major. 
Betelguese, a star of the first magnitude in the left shoulder of 

Orion. 
Bissextile, or leap year, every fourth year. 
Bootes, a brilliant constellation of the northern hemisphere. 
Brandenburgium Sceptrwn, the Brandenburgh sceptie, a small 

southern constellation. 
Cancer, the crab, a constellation of the zodiac in the northern 

hemisphere. 
Canis Major, the great dog, a beautiful constellation of the south- 
ern hemisphere. 
Canis Minor, the little dog, a constellation of the northern hemi- 

phere under Gemini. 
Canopus, a star of the first magnitude in Argo Navis. 
Capellu, a brilliant star of the first magnitude in thebackof Auriga. 



GRAMMAR. OF ASTRONOMY. lg$ 

Getpricoftms, the goat, a constellation ot the zodiac. 

Cardinal points, the east, west, north, and south points of the 

compass. 
Cardinal points of the ecliptic, the first degrees of the signs, Ari-esi, 

Cancer, Libra, and Capricornus. 
Cassiopeia, a northern constellation, representing a lady seated. 
Castor, a star of the first magnitude in Gemini. 
Cela Sculptoris, the graver, a small modern constellation of tlie 

southern hemisphere. 
Celestial, heavenly. 

Centauries, a beautiful constellation of the southern hemisphere. 
Centrifugal force, that force by which a body revolving around 

another, endeavours to recede from it. 
Centripetal force, that force by which a body revolving around 

another, is drawn towards the centre of gravity. 
Centre of gravity, that point about which all the parts of a body 

do, in any situation, balance each other. 
Cepheus, a. constellation within the arctic circle. 
Cerberus, a small northern constellation in the hand of Hercules. 
Ceres, one of the asteroids. 
Cetus, the whale, a large southern constellation. 
Chameleon, a new constellation within the antarctic circle. 
Cliara, the southern hound in Canes Venatici. 
Circinus, the compasses, a small southern constellation at the feet 

of Centaurus. 
Circles of the sphere, imaginary lines surrounding the sphere. 
Columba JYoachi, Noah's dove, a small constellation of the south- 
, em hemisphere below Orion. 
Colures, two great circles of the sphere. 
Coma Berenices, Berenice's hair, a northern constellation, 
Complement of an-arc, or an angle, what it wants of 90°. 
Conjunction of two bodies, when they appear in the same sign of 

the zodiac. 
Constellation, a cluster of 'stars, which authors have supposed to 

resemble the outlines of some animal. 
Cor Caroli, Charles' heart, a single star of the second magnitude 

between Asterion and Chara. 
Cor Hydra, a star of the second magnitude in the heart of 

Hydra. 
Corona Australis, the southern crown, a circle of stars around the 

foot of Sagittarius. 
Corona Borealis, the northern crown, a small brilliant constella- 
tion in the northern hemisphere. 
Corvus, the raven, a small southern constellation in the back of 

Hydra. 
Cosmical rising and setting of a celestial body, when it rises and 

sets with the sun. 
Crater, the cup, a small southern constellation below Leo 
Crepusculum, twilight. 

o 



154 GRAMMAR OF ASTRONOMY. 

Crux, the t ross, a small constellation near the south pole. These 

stars serv« as pointers to the south pole. 
C/ilminetimi, th^> passage of a 9tar or planet across the meridian. 
Cycle ofthemcxm, a penod of 19 years, when the conjunction and 

lunar aspects, will again bear nearly the same appearance 
Cycle of the sun, a period of 28 years, when the days of the month 

Will ugaiu return to the^hme days of the week. 
Cygvius, the swan, a beautiful northern constellation. 
Day, ( artificial,) the time from sunrise to sunset 
Day, (astronomical.) the lime between the sun's appearing- twice 

on the same meridian. 
Day, (civil,) in the United States and England, it is twice 12 

hours, reckoned from midnight to midnight. 
Day, (natural,) the time in which the earth makes a complete re- 
volution on its axis. 
Day, (sidereal,) the time elapsing between a star's appearing-, 

twiee successively ov, the same meridian. 
Declination, the distance of a celestial body from the equinoctial 

or equator, in degrees. 
Degree, the three hundred and sixtieth part of a circle. 
Delpldnus, the dolphin, a small bright constellation of the southern 

hemisphere. 
Deneb, a star of the first magnitude in Leo. 
Depression of a celestial body, its distance below the horizon. 
Descending node, that point of the ecliptic where the orbit of a 

planet is supposed to intersect it in passing from a northern to a 

southern latitude. 
Diagram, a delineation of geometrical figures; a mathematical 

scheme. 
Digit, the 12th part of the diameter of the moon or sun. 
Disk, the round face of the sun, or of a planet. 
Diurnal, daily. 

Dorado, the sword fish, a new southern constellation. 
Draco, the dragon, a northern constellation surrounding the pole 

of the ecliptic 
Dubhe, a star of the first magnitude in Ursa Minor. 
Earth, the planet in which we live, the third in order from the sun. 
East, one of the cardinal points. 
Eccentricity, deviation from a centre ; the distance between the 

centre of an ellipse, and either of the foci. 
Eclipse, an obscuration of the light of one body, occasioned by 

the interposition of another. 
Electra, one of the Pleiades. 
Ecliptic, the earth's orbit round the sun. 
Elebation, the height or altitude of any object. 
Ellipsis, an oval figure generated from the section of a cone, by 

a plane catting both sides of the cone, but not parallel to the 

base, and meeting with the base produced. 
Elongation, the angular distance of a planet from the sun> as it 

;*t>?»ears to a <necfatcr on the e^irth* 



GRAMMAR 431' ASTRONOMY. 1-55 

Emersion., the time when a planet begins to recover its light, after 

having been eclipsed. 
Epact, the difference between a lunar and a solar year. 
Ephemeris, a collection of tables containing an acctmnt ©f the 

daily motions and situations of the planets. 
Epoch, see Era. 
Equation of time, the difference between solar time, aad that 

shown by a clock. 
Equator, a great circle of the sphere, which divides the globe into 

northern and southern hemispheres. 
Equinoxes, those points where the ecliptic cuts the equator ; the 

first degrees of Aries a«d Libra. 
Equuleus Pictoris, the painter's easel, a small constellation of the 

southern hemisphere under Argo Navis. 
Equulus, the little horse, a northern constellation representing a 

horse's head. 
Eridanus, the river Po, a large constellation of the southern hem- 
isphere. 
Etanin, a star of the second magnitude in the head of Prace. 
Eviction, inequality in the motion of the moon 
Fac-ulce, bright spots frequently seen on the sun's disk. 
Firmament, the orb of the fixed stars. 

Fixed Stars, those stars that do not appear to change their position. 
Focus of an ellipse, a point towards each end of the longer axis 
of an ellipse, at the distance of half the length of the transverse 
from either extremity of the conjugate 
Foci, plural of focus. 

Fomalkavl, a star of the first magnitude in Australia 
'Fornax Cbjmica, the chymist's furnace, a new southern constella- 
tion. 
Galaxy, or milky-way, a large band of light encompassing the 

heavens. 
Gemini, the twins, a constellation of the zodiac. 
Gemma, or Alphacca, a brilliant star of the second magnitude in 

Corona Borealis. 
Geocentric pfa.ce of a planet, its position as seen from the earth. 
Georgium Sidus, a name given to the planet Herschel in honour 

of George III. 
Gibbous, the shape of the enlightened part of the moon from the 

first quarter to the full. 
Gms, the crane, a new constellation of the southern hemisphere. 
Halo, a circle surrounding the sun or moon. 
Heavens j the wide expanse in which the sun, planets, stars, and 

comets are situated. 
Heliacal rising and setting of a star or planet, when it emerges 
from the sun's rays, and appears above the horizon before mm, 
in the morning. 
Heliocentric place of a star or plamt, itsjjosition as seen fr«'m tile 
sun. 



tOP GRAMMAR OF ASTRONOMY. 

Hemisphere, half a sphere 

Hercules, a northern constellation. 

Hercules, a name given to the star Pollux. 

Hcrschel, Uranus, or the Georgium Sidus, the last planet in the 
solar system. 

Hesperus or Vesperus, the name of Venus when an evening star. 

Hettroscii, inhabitants of the temperate zones; so called because 
their shadows fall but one way at noon. 

Horizon, a great circle of the sphere dividing the earth into up- 
per and lower hemisphere. The sensible horizon is that which 
bounds our sight. 

Horizontal, belonging to the horizon ; parallel to the horizon. 

Horizontal parallax, the parallax of a celestial body, when rising. 

Horologium, the clock, a new southern constellation. 

Hour, the twenty -fourth part of an astronomical day. 

Hour-circles, the same as meridians. 

Hmdes, a group of stars in the head of Taurus ; the chief of 
which is Aldebaran. 

Hydra, a large southern constellation, represented as a serpent 
with a number of heads. 

Hudrus, the water snake, a small antarctic constellation. 

Hydra Cor, a star of the first magnitude in Hydra. 

Hupjthesis, a supposition. 

Immersion, when a planet enters into a dark shadow, or the mo- 
meat of an eclipse. 

Inclination^ an angle which the orbit of one planet makes with 
that of another. 

Indus, the Indian, a new southern constellation under Sagittarius. 

Inferior planets, the planets whose orbits are between the earth 
and sun. 

Ingress, the time of the sun's entering into any particular sign. 

Intercalary day, the odd day made up every fourth year of the 
6 hours over 36.5 days. 

Julian year, the year instituted b}' Julius Cesar, called old style. 

Juno, one of the four Asteroids. 

Jupiter, the largest of all the planets. 

Kochab, a star of the second magnitude in Ursa Minor. 

Lacerta, the Lizard, a small northern constellation near Andro- 
meda. 

Ijoiitude of a place, its nearest distance from the equator. 

Latitude of a planet or star, its nearest distance from the ecliptic. 

Ijeo Major, the great lion, a constellation of the zodiac. 

Leo Minor, the little lion, a new constellation above Leo Major, 

formed by Hevelius 
Lepus, the hare, a southern constellation at the feet of Orion. 

jLess circles of the sphere, those which divide the globe into un- 
equal parts. 
Libra, the halarrce, a constellation of the'zodiac-. 



GRAMMAR OF ASTRONOMY. 15? 

Zdbration, an inequality in the moon's motion whereby one side 

is more towards ihe earth than the other. 
Line of the Aspides, a line joining the aphelion and perihelion 

of a planet's orbit. 
Lines of Longitude, meridians. 

Longitude of a place, its distance east or west from the first me- 
ridian. 
Longitude of a star or planet, its distance from the first degree 
of Aries, reckoned on the ecliptic eastward, in signs, de- 
grees, &o. 
Lucifer, name given by the Romans to Venus when a. morning 

star. 
Luminaries, the sun, planets, stars, and comets. 
Lunar aspects, aspects of the moon. 

Lumr distances, the moon's distance from the sun or a fixed star. 
Lunation, the time from one new moon to another, it being 

about 29 days VI hours 44 minutes and 3 seconds. 
Lupus, the woif, a southern constellation near Centaurus, who is 

represented as piercing it with a spear. 
Lynx, a new constellation of the northern hemisphere near 

L'rsa Minor. 
Lyra, the harp, a northern constellation. 
Macula-., dark spots appearing on the sun's disk. 
Magnitudes, the comparative sizes of the heavenly bodies. 
Markaby a star of the second magnitude in the wing of Pegasus. 
Mars, the planet next in order from the earth, of a ruddy ap- 
pearance. 
Menkar, a star of the second magnitude in the mouth of Cetus 
Mercury, the planet nearest the sun. 
Meridian, a great circle of the sphere, passing through the ze* 

nith and poles, and crossing the equator at ri&ht angles, 
Merope, one of the Pleiades. 
Microscope, an optical instrument, by which we are enabled to 

discover very minute objects. 
Microscopium, the microscope, a new constellation of the south- 
ern hemisphce below Capricornus. 
Milky-way, the galaxy, anlnnumerabie multitude of stars reach- 
ing across the heavens. 
Minute, the 60th part of an hour or of a degree. 
Mirach, a star or the second magnitude in the zone of Andro- 
meda ; also a star of the third magnitude in the girdle of 
Bootes. 
Mizar, a star of the third magnitude in the tail of Ursa Minor. 
Momentum, the quantity of motion in a moving body. 
Monoceros, the unicorn, a modern constellation on the equator, 

between Orion and Hydra. . 
Mons Mcenalus, mount Mrenalus, a small constellation of tire 
northern hemisphere between Vino and Serpens. 
O 2 



L58 -jrammag. of astronomy. 

..tftms Mensas, the table mountain, a small constellation within 
the antarctic circle. 

.Month, (lunar periodical,) 27 days 7 hours 43 minutes 8 seconds; 
the time the rnoon occupies in passing from a point in her 
orbit to the same point again. 

Jfonth, (lunar synodical,) the time taken up between two con- 
junctions, of the sun and moon; or 29J days nearly. 

.Month, (calendar or solar,) the 12th partofa year. —It averages 
about 30£ days. 

.Mooa,the satellite of the Earth. 

Musca, the fly, a small northern constellation near the back of 
Aries. 

Musca Australia, the southern fly, a southern constellation. 

.Mutual aspects, such as the primary planets make among them- 
selves. 

.Xadir, a point in the heavens directly opposite to the zenith. 

J\Tehula>, telescopic stars having a cloudy appearance. 

Nocturnal Arc, the arc described by a celestial body from its 
setting to its rising. 

.Xodes, two points where the orbit of a planet intersects the 
plane of the ecliptic. 

Nongesimal degree, the highest point of the ecliptic above the 
horizon, or the 90th degree, equal to the angles the ecliptic 
makes with the horizon. 

Noon, mid-day, the time of the sun's appearing on the meridian. 

North, one of the four cardinal points. 

Norma, or Quadra Euclidis, a southern constellation. 

Nucleus, a name given to the head of a comet. 

Nutation of the earth's axis, a libratory motion of the earth, 
occasioned by the attraction of the sun and moon upon the 
protuberant matter of the equator. 

fjhtique, indirect ; not perpendicular. 

Obliquity, deviation from physical rectitude ; deviation from 
parallelism, or perpendicularity. 

Gblimf.e sphere, that position of the globe in which either of the 
poles is elevated above the horizon any number of degrees 
less than 90. 

flcculiaiion, the obscuration of a celestial body by the interpo- 
sition of the moon, or some other planet. 

Octans Hadleianus, Hadley's Octant, a new southern constella- 
tion near the south pole. 

Octant, an eighth part of a circle. 

Ojjicina Scutptoris, the sculptor's workshop, a new southern con- 
stellation below Cetus. 

Opposition, the position of the stars or planets when 130° de- 
gress distant from each other. 

Orbit, the curve that any celestial body describes in perform- 
ing, its revolution around another celestial body. 



GRAMMAR OF ASTRONOMY. 1 50 

Oriental, eastern. 

Orion, a brilliant constellation near the equator. 

Pallas, one of the Asteroids. 

Parallax, the angle which the semidiameter of the earth forms 

with a celestial body. 
Parallels of latitude, small circles of the sphere drawn parallel 

to the equator. 
Parallel sphere, the position of the sphere in which the equator 

is parallel to the horizon. 
Pavo, the peacock, a new constellation of the southern hemi- 
sphere. 
Pegasus, a northern constellation representing a winged horse. 
Penumb7*a, a faint shade surrounding the perfect shadow in an 

eclipse. 
Perigee, that point of the moon's orbit nearest the earth. 
Perihelion, that point of a planet's orbit nearest the sun 
Periscii, the inhabitants of the frigid zones. 
Period, in astronomy., the time in which any phenomenon is 

completed so as to begin again the same as before. 
Periphery, the circumference of any circle or ellipse. 
Periccci, those people who live in the same latitude, but on op- 
posite longitudes. 
Perseus, a northern constellation represented with a sword in 

one hand, and a head covered with snakes instead of hair, in 

the other. 
Phases, the different appearances of the enlightened pavt of the 

moon or inferior planets. 
Phenomenon, a remarkable appearance in the heavens; as 

eclipses, comets, &c. 
Phainix, a southern constellation, representing a fabulous bird 

of the ancients. 
Pisces, the fishes, a constellation of the zodiac. 
Piscis Autralis, the southern fish, a brilliant constellation of the 

southern hemisphere. 
Piscis volans, the flying fish, a modern constellation near the 

south pole. 
Planet, (primary,) a celestial body which revolves around the 

sun. 
Planet, (secondary,) a celestial body that revolves around a 

primary planet. 
Plane, in astronomy often means imaginary surface, as the 

plane of a planet's orbit. 
Planetarium, or orrery, an instrument used to demonstrate the 

various phenomena of the planets. 
Pleiades, a brilliant cluster of stars in Taurus. 
Pointers, two stars in Ursa Major, which always point to the 

pole star. 
Polar circks : two small circles of the sphere 23° 23' from either 

pole. 



l60 GHAMMAtt OF ASTRONOMY. 

Polaris, the pole star, a star of the second magnitude in Ursa 

Minor. 
Poles, the extremities of a planet's axis. 
Pollux, a bright star of the second magnitude in Gemini. 
Precession of the equinoxes. See Recession of the equinoxes. 
Procyon, a star of the first magnitude in Canis Major. 
Quadrans Euclidis, Euclid's quadrant, a small modern constel- 
lation of the southern hemisphere near Scorpio. 
Quadrant, the fourth part of a circle. 
Quadratures, or quarters, the position of the moon when 3 signs 

from the sun 
Quart He aspect, the position of two celestial bodies when 3 signs 

distant. 
Ras ./Ugethi, a star of the third magnitude in Hercules. 
Ras Alhagus, a star of the second magnitude in Serpentarius. 
Rastabcn, a star of the second magnitude in the head of Draco. 
Radius, half the diameter of a circle. 
Recession of the equinoxes, a slow retrograde motion of the two 

points where the equator intersects the ecliptic. — It equals 

50J seconds a year. 
Refraction, the variation of a ray of light from that right line in 

which it would have passed, had not the density of the medium 

turned it aside. 
Reflection, the return of the rays of light after being repelled or 

driven backwards. 
Regulus, a star of the first magnitude in the heart of Leo. 
Repulsion, that power in bodies which prevents the approach of 

others ; the act or power of driving off from itself. 
Retrograde, the act of moving backwards; or, a motion in the 

planets contrary to the order of the signs. 
Revolution, the period of a celestial body. 
Rigel, a star of the first magnitude in the heel of Orion. 
Rising of a celestial body, its appearance above the eastern edge 

of the horizon. 
Robur Caroli, Charles' oak, a new constellation of the northern 

hemisphere. 
Rotation, the motion of a celestial body on its axis. 
Sagitta, the arrow, a northern constellation. 
Sagittarius, the archer, a constellation of the zodiac. 
Saros, Chaldean Saros, 18 years II days 7 hours 43 minutes 

20 seconds, or 223 lunations ; the time in which the same 

eclipse returns. 
Satellites, or moons, secondary planets which revolve around 

primary ones. 
Saturn, one of the primary planets. 
Scheat Alperas, a star of the second magnitude in the leg of 

Pegasus. 
Schedir, a star of the second magnitude in Cassiopeia. 
Scorjno, the scorpion, a constellation of the zodiac. 



GRAMMAR OF ASTRONOMY. ltil 

Scutum Sobieski, Sobieski's shield, a small northern constella- 
tion formed by Hevelius. 

Second, the 60th part of a minute. 

Serpeniarius et Serpens, a northern constellation. 

Setting of a planet, its disappearance in the western horizon. 

Sextans Uranice, Urania's sectant, a modern constellation on 
the equator near Leo. 

Sextant, the sixth part of a circle ; a mathematical instrument. 

Sextile aspect of heavenly bodies, when they are 60° distant. 

Sideral or Sidereal., belonging to the stars. 

Sign, the 12th part of the ecliptic ; or 30 degrees. 

Sirius, a brilliant star of the first magnitude in the head of Canis 
Major. 

Situla, a star of the third magnitude in Aquarius. 

Solstices, the time the sun enters Cancer and Capricorn. 

Solstitial points, the first degrees of Cancer and Capricorn ; 
those points where the ecliptic touches the tropics. 

South, a cardinal point in the horizon. 

Southing of the stars, &c, the time when they culminate. 

Sphere, in astronomy, that concave expanse which invests our 
globe. 

Sphere, (artificial,) an instrument representing the several cir- 
cles of the sphere in their natural order. 

Sphere, (oblique,) that in which the axis and equator cut the 
horizon oblique]) 7 . 

Sphere, (parallel,) when the equator as well as all its parallels 
are parallel to the horizon. 

Sphere, (right, or direct,) that which "has the poles of the world 
in its horizon, and the equator in the zenith and nadir. 

Spica Virginisy the virgin's wheat-ear, a brilliant star of the first 
magnitude in Virgo. 

Stars, those bodies which shine by their own effulgence. 

Stationary, standing still ; without motion. 

Style, in astronomy, time reckoned from some particular period. 

Superior planets, those which revolve without the orbit of the 
earth. 

Syzygy, that part of a planet's orbit in which it is either in 
conjunction or opposition. 

Tangent, a line touching a circle perpendicular to the radius. 

Tarandus, the rein-deer, a modern constellation within the arc- 
tic circle. 

Taurus, the bull, a constellation of the zodiac. 

Taurus Poniaiowski, Poniatowski's bull, a modern constellation 
of the northern hemisphere below Hercules. 

Telescopic stars, those seen only by means of a telescope. 

Telescopium, the telescope, a new southern constellation, formed 
in commemoration of HerschePs great discoveries with his 
telescope. 



1 62 GRAMMAR OF ASTRONOMV. 

Temperate zones, that proportion of the earth contained between 
the tropics and the polar circles. 

Terminator, an imaginary circle dividing the enlightened hemi- 
sphere of the earth from the darkened. 

Theory, a plan or system yet subsisting in the mind ; a specu- 
lative scheme. 

Tides, the rising and falling of the waters, caused by the attract- 
ive action of the sun and moon. 

Time, the measure of duration. 

Torrid zone, that part of the earth contained between the tropics. 

Toucana, the toucan, or the American goose, a southern con- 
stellation. 

Transit, the passage of an inferior planet over the sun's disk. 

Triangulum, the triangle, a northern constellation of small stars. 

Triangulum Australe, the southern triangle, a modern constel- 
lation on the antarctic circle 

Tropics, two small circles of the sphere, 23° 28' on either side 
of the equator. 

Twilight, faint light before sunrising and after sunsetting, oc- 
casioned by the refraction of the earth's atmosphere. 

Umbra, the total shadow of the sun or moon in an eclipse. 

Uranus, the Georgium Sidus, or Herschel, the most distant pla- 
net in the solar system, discovered by Dr. Herschel. 

Ursa Major, the great bear, a splendid northern constellation. 

Ursa Minor, the little bear, a constellation near the north pole 
resembling Ursa Major. 

Vega, the brightest star in Lyra. 

Venus, a planet of the solar system, situated between the orbits 
of Mercury and the earth. 

Vertex, that point in the heavens directly over our heads. 

Vertical circles, the azimuth circles. 

Vesta, one of the new planets. 

Vindemiatrix, a star of the third magnitude in ihe north wing 
of Virgo. 

Virgo, the virgin, a constellation of the zodiac situated on the 
equator. 

Vulpecula et Anser, the fox and goose, a modern constellation 
in the northern hemisphere. 

Xiphias, a southern constellation. 

Year, that space of time occupied by a primary planet in per- 
forming its revolution round the sun. 

Zenith, that point in the heavens exactly over head ; the upper 
pole of the horizon. 

Zodiac, a zone surrounding the heavens, in which space all the 
planets perform their revolution around the sun. 

Zone, a division of the sphere contained between two parallels 



fautntionu for EvumlnutlQU. 



1. Define the term Astronomy, and name those bodies 
which are called the celestial luminaries. 

Of the History of Astronomy. 

1. What people were the early cultivators of astronomy ? 

2. To what use did the Phoenicians apply this science ? 

3 What was the particular objeci of their observations ? 

4. What is related of Thales? 

5 What invention is ascribed to Anaximander? 

6. How did the Greeks improve their knowedge of astro- 
nomy ? 

7. Did the Romans encourage this science ? 

8. By whom has astronomy been brought to its present 
state of perfection ? 

9. Who were the most noted among the ancient astrono- 
mers ? When did Pythagoras flourish ? What was his 
system of the universe ? What planets were known in his 
time ? 

10. W T hen did Ptolemy flourish ? Give a description of 
his system. 

11. During what time was astronomy neglected? 

12. When did astronomy begin to assume a rational ap- 
pearance ? 

13. Who revived the system of Pythagoras ? At what 
time ? 

14. Did the system of Pythagoras meet with opposition ? 

15. Did tfTycho Brahe oppose the opinions of Coperni- 
cus ? 

16. Describe the system which Tycho projected. 

17. Did it succeed ? 

18 What is said of Kepler ? 

19. What discoveries is Galileo said to have made ? 

20. To whose labours are we indebted for improvements 
in astronomy ? 



164 GRAMMAR OF ASTRONOMIC 

Of the Solar System. 

1. What system is now received as the true one ? 

2. What bodies does it comprise ? 

3. What are the primary planets ? 

4. Which of them are called asteroids ? 

5. What is understood by secondary planets ? 

6. What are comets? 

7. What is the centre of the system ? In what order do 
the planets move? 

8. What is the orbit of a celestial body ? 

9. What is understood by the term year ? What, by day ? 

10. What is the axis of a planet ? 

11 Of what shape are the sun and planets? 

12. Define the term globe, or sphere. 

13. Why are the sun and planets supposed to be globu- 
lar? 

14. What combines to prove that the earth is globular ? 

15. What is the zodiac ? How divided ? 

16. What is the ecliptic ? 

Of the Sun. 

1. Can you give a description of the sun ? What is its 
diameter ? What, the period in which it revolves on its 
axis ? 

2. When is the sun nearest to the earth ? 

3. Why is it hotter in summer than in winter ? 

4. What is supposed to environ the sun ? and how are 
its light and heat occasioned ? 

5. Give the supposed extent and density of the atmo- 
sphere surrounding the sun. 

6. What occasions the appearance of the sun's rising in 
the east, and setting in the west ? 

7. When is it noon at any place ? and when midnight ? 

8. How has the period of the sun's revolution been as- 
certained ? 

Of Mercury. 

1. Give some description of Mercury. 

2. What is his diameter ? 

3. What, the time of his revolution ? 

4. What, the length of his day ? 

5. Where does he cross the plane of the ecliptic ? 

6. What is the velocity of Mercury ? What, his eccen 
tricitv-? 



GRAMMAR OF ASTRONOMY. 1 65 

7. What is understood by eccentricity in astronomy ? 

8. What is said of Mercury when viewed through a tele- 
scope ? 

9. What is called a transit ? How many have been ob- 
served ? 

10. What is meant by the sun's disk ? 

Of Venus. 

1. Give some description of Venus. 

2. What is her diameter ? and what, her circumference ? 

3. What, her mean distance from the sun ? — her eccen- 
ticity ? — her movement in orbit ? 

4. What time does Venus take in performing an annual 
revolution ? — a diurnal rotation ? 

5. What appearances has she similar to those of the 
moon? 

6. Do transits of Venus ever occur ? When was one ob- 
served ? 

7. When will any happen again ? 

8. When is Venus a morning star? — an evening star ? 

9. What have been observed on the disk of this planet ? 
what is the supposed magnitude of its mountains, compared 
with those of the earth ? 

10. Where does the orbit of Venus cut the plane of the 
ecliptic ? 

11. By what is Mercury surrounded? 

OflheEarlh. 

1. Give some description of the earth. 

2. What is its distance from the sun ? What, its move- 
ment in orbit ? 

3. What is the difference in length between the polar and 
the equatorial diameter of the earth ? What is the eccen- 
tricity of the earth ? 

4. What is the circumference of the earth, measured 
round the equator ? — through the poles ? 

5. In what time is its sidereal revolution performed ? — 
Its tropical revolution ? its revolution on axis ? 

6. What is meant by the sidereal revolution of the earth ? 
and what, by the tropical ? 

7. What is the recession of the equinoxes ? 

8. What is the length of the natural day ? 

9. What is a meridian ? 

10. How many motions has the earth, and what are they 
called ? 

P 



166 GRAMMAR OF ASTRONOMY. 

11. What produces the change of seasons ? — the succes- 
sion of day and night? 

12. What is called the obliquity of the ecliptic ? 

13. How great can the sun's greatest declination be? 

14. How is the apparent declination occasioned ? 

15. When are the days the longest, and when the short- 
est, in each hemisphere respectively ? 

16. What are called the solstitial points ? 

17. At what time are the day? and the nights equal? 

18. When is the earth said to be in its equinox ? 

19. What is the sun's declination at the solstices ? and 
what, in the equinoxes ? 

20. Mention those days on which the sun enters the first 
degree of each sign of the zodiac respectively ? 

21. What surrounds the earth ? 

22. What attends the earth in its revolution about the 



Of Mars. 

1. Give some description of Mars. 

2. How does this planet appear when viewed through a 
telescope ? How does it appear to move ? 

3. In what time does it perform an annual revolution ? 
and at what distance from the sun ? What is its diameter ? 
— the eccentricity of orbit ? How rapid is its movement? 

4. What is the length of its day ? 

5. What angle does the orbit of Mars make with the 
ecliptic? Where is the place of his ascending node? 

6. At what time is Mars seen ? 

7. At noonday where is he sometimes seenf What do 
you infer from this circumstance ? 

8. How would the earth appear to the inhabitants of Mars t 

Of the four Asteroids or Minor Planets. 

1. Give some description of Vesla. 

2. What is the length of its diameter? and what, its 
mean distance from the sun ? What is the length of its 
year ? and what, the velocity of its movement ? How great 
is the eccentricity of its orbit ? 

3. When and by whom was Juno discovered ? Give some 
description of it. 

4. What is its diameter ? and what its distance from the 
sun ? What. is the length of its year ? Its eccentricity ? 

5. Give some description of Ceres. 

6. What is the length of its diameter ? and what, its dfc* 



GRAMMAR OF ASTRONOMY. 167 

tance from the sun ? In what time does it perform its an- 
nual revolution ? and at what rate ? How great is the ec- 
centricity of its orbit ? 

7. What is the height of its atmosphere ? 

8. By whom and when was Pallas discovered ? What is 
its appearance ? 

9. What is the estimated diameter of Pallas? and what 
its distance from the sun ? 

10. to what time does it revolye around the sun ? and 
what is its eccentricity ? 

11. Why does the orbit of Pallas cross that of Ceres ? 

Of Jupiter. 

1. What is the situation of Jupiter ? 

2. V\ hat is his diameter ? and what, his distance from 
the sun ? 

3. What is the length of Jupiter's year ? and what is his 
hourly motion ? 

4. What is the length of his day ? 
5 Why no change of seasons ? 

6. What season in the polar regions of Jupiter ? and 
what about his equator ? 

7. How is his appenrance, compared with Venus ? 

8 When does Jupiter appear as a morning star ? — an 
evening star ? 

9. What angle does he form with the plane of the eclip- 
tic? 

10. How much larger does the sun appear to us, than to 
those who inhabit Jupiter ? 

11. Jupiter appears to be surrounded with belts — give 
some description of them How has the time of Jupiter's 
rotation on its axis been ascertained ? 

12. What attend this planet ? What benefit are thev to 
it? 

Of Saturn. 

1. How is Saturn situated? 

2. What is the length of his diameter ? and what is his 
circumference ? 

3. What is the length of his annual revolution ? and how 
great is his velocity ? 

4. What angle does Saturn's orbit form with the ecliptic ? 
How great is his eccentricity ? Where his ascending node ? 
and where, his descending node ? 

5. What is the length of his day, or daily revolution '■ 



168 GRAMMAR OF ASTRONOMY. 

6. What is his appearance to the naked eye ? 

7. Describe his appearance, as viewed through a tele- 
scope. „ 

8. What things are said concerning Saturn's ring ? 

9. Describe the distances and breadths of the rings. 

10. What are Saturn's zones similar to ? 

11. What conjectures have been entertained respecting 
Saturn's ring ? 

12. Describe Saturn's satellites, namely, their number, 
and by whom discovered ? 

Of Herschel. 

1. Give some description of this planet. 

2. What is its diameter, and its mean distance from the 
sun ? 

3. What is the length of its year ? Has the time of its 
daily revolution been ascertained ? How great is its move- 
ment in orbit ? 

4. How great an angle does Herschel's orbit form with the 
plane of the ecliptic ? What is its eccentricity ? Where is 
its ascending node ? — its descending node ? 

5. How can a planet be distinguished from a fixed star? 

6. How many moons attend Herschel ? 

7. How much more heat does the earth derive from the 

sun than Herschel does ? 

i 

Of the Secondary Planets. 

1. What is a secondary olanet ? 

2. What is observed respecting its gravitation and move- 
ment ? 

Of the Moon. 

3. Describe this planet. 

4. How far is it from the earth ? and how far from the 
sun r In its orbit how many miles does it move an hour? 

5. in what time does it turn once around on its axis ? 

6. What are meant by the phases of the moon ? How 
does the moon sometimes appear ? 

7. When is it new moon ? 

8. When, full moon ? 

Of the Satellites of Jupiter. 

9. What makes up for Jupiter's deficiency of light from 
the sun ? Who discovered Jupiter's satellites? 

10. How far from Jupiter is his first satellite ? and in 
what time does it revolve around him ? 



GRAMMAR OF ASTRONOMY. l69 

11. How far, the second ? and what is the time of its re- 
volution ? 

12. How far, the third ? and what is the time of its revo- 
lution ? 

13. How far the fourth ? and what is the time of its revo- 
lution ? 

14. How are Jupiter's satellites important in finding the 
longitude of places ? Which is considered the best for this 
purpose ? and why ? 

15. In what work are the immersions and emersions of 
Jupiter's satellites found calculated ? 

16. Describe the angles of the orbits of Jupiter's moons, 
as seen from the earth. 

Of the satellites of Saturn. 

17. How many satellites has Saturn ? 

18. Describe the distances, and the time of revolution of 
the first satellite. 

19. — of the second satellite. 

20. — of the third satellite. 

21. — of the fourth satellite. 

22. — of the fifth satellite. 

23. — of the sixth satellite. 

24. — of the seventh satellite. What has been observed 
of this satellite. 

Of the satellites of Herschel. 

25. How many satellites has Herschel ? and by whom 
were they discovered ? 

26. Mention the time occupied by the first satellite in 
revolving around its primary ; and the distance from its 
primary, at which it revolves. 

27. Mention the distance, and the time of revolution, of 
the second satellite. When was it discovered ? 

28. In what time does the third perform its revolution ? 
when was it discovered ? 

29. How far from Herschel is the fourth ? and in what 
time does it revolve ? When was it discovered ? 

30. In what time does the fifth complete its revolution, 
and at what distance ? W 7 hen was it discovered ? 

31. In what time the sixth ? and at what distance ? 

32. W'hat is observed respecting- the orbits of Herschel's 
satellites ? 

Of Comets. 

1. What are comets ? What is their appearance ? 

2. Do they ever approach near to the sun ? 

2 P 



170 GRAMMAR OF ASTRONOMY. 

o. What is said concerning their movement ? 

4. What was the opinion of the ancients respecting 
comets r 

5. What conclusion did Newton form with regard to 
comets ? 

6. When is the movement of comets accelerated ? when 
retarded ? 

7. How near to the sun did the comet of 1680 approach ? 

8. What appears to affect comets ? 

9. How many comets have been observed ? the elements 
of how many have been ascertained ? 

10. How many comets appear to have passed between 
the orbit of Mercury and the sun ? — between the orbit of 
Mercury and that of Venus ? — Venus and the earth ? — the 
earth and Mars ? — Mars and Ceres ? — Ceres and Jupiter ? 

11. What is said of the magnitudes of comets ? 

12. What is said of the bright train of comets? 

13. The system of comets somewhat in obscurity — upon 
whose opinions must we depend respecting them ? 

Of the Fixed Stars. 

1. Give some description of the fixed stars. 

2. What difference is there in appearance between the 
fixed stars and the planets ? 

3. What motion do the fixed stars appear to have ? 

4. Why does the north star appear immoveable ? 

5. How many stars are visible to the naked eye ? why 
does there appear to be such a multitude ? 

6. Are the fixed stars any larger in appearance when ob- 
served through glasses ? 

7. How have these stars been divided ? 

8. What stars are called unformed stars ? what periodi- 
cal stars ? 

Of ike Constellations. 

1. What is a constellation? 

2. Into how many constellations are stars classed? and 
how many in the zodiac ? in the northern hemisphere ? — 
in the southern hemisphere ? 

Of motion. 

1. What is the definition of motion? With how many 
kinds of motion are we principally acquainted ? 

2. W T hat effect upon bodies has heat ? and what has cold ? 

3. In the consideration of motion what things must be 
attended to ? 



GRAMMAR OF ASTRONOMY. If! 

4. In a mechanical sense what property does every body 
possess ? 

5. If not resisted how will a body move when put in 
motion ? How is velocity of motion estimated ? 

6. When a body tends to some particular point, what 
will be its motion ? what will produce a curvilinear direc- 
tion ? 

7. What will be the motion of a body with respect to its 
moving force ? 

8. What will be the motion when several powers are dif- 
ferently applied at the same time ? 

& How many forces act upon a body moving in a cur- 
vilinear direction ? 

10. What is called the centrifugal force ? and what the 
centripetal force ? 

11. What is called the centre of gravity of a body ? 

12. Where may the weight of a body be considered as 
centered ? 

13. What is the common centre of gravity of any two or 
more b dies ? 

14. How may motion be divided ? What is real motion ? 
What is apparent motion ? 

Of Eclipses. 

1. What is an eclipse ? 

2. How do you account for the appearance of an eclipse? 

3. How many kinds of eclipses are there ? 

4. What is an eclipse of the sun? and how is it occa- 
sioned ? 

5. When do eclipses of the sun happen ? 

6. What is a partial eclipse ? 

7. What is a total eclipse? 

8. When will an eclipse of the sun be central ? 

9. W r hat is an annular eclipse ? 

10. What is an eclipse of the moon ? 

11. Describe the figure of the earth's shadow. 

12. What is a partial eclipse of the moon ? 

13. What phenomenon would occur, if the earth's orbit 
and the moon's were in the same plane ? What are called 
the moon's nodes ? 

14. What is observed of the eclipses of Jupiter's satel- 
lites ? 

Of Tides. 
1. What is tide? 
Si. How often do the tides ebb and flow every lunar dav ? 



172 GRAMMAR OF ASTRONOMY. 

3. How much of the earth's surface is covered with 
water ? 

4. What space of time does the tide occupy in ebbing 
and in flowing ? 

5. What is observed respecting the time of high water ? 

6. How much greater is the influence of the moon upon 
the tides than that of the sun? 

7. How many kinds of tides are there ? and what are 
their effects ? 

8. When do the flux and reflux of the tides become 
spring tides ? When neap tides ? 

9. When do the greatest tides happen ? Why ? 

10. What is said of the tides when the moon is in the 
equator ? and what when she declines ? 

11. How are tides retarded? and what is the effect? 

12. What is observed of the tides of the German ocean ? 

13. Why have lakes no tides ? 

14. What is said of the elevation of tides in the Medi- 
terranean and the Baltic sea t 

15. Where do the tides rise very high ? 

Of Aim asp here. 
1 What is atmosphere ? To what is it necessary ? 

2. To what height is the atmosphere of the earth per- 
ceptible ? Of what does it consist ? 

3. What is the pressure of the atmosphere upon every 
foot of the earth's surface ? 

4. What is the figure of the atmosphere ? 

Of Wind. 

1. What is wind ? To what cause may we attribute the 
wind ? 

2. What kinds of winds are there ? 

3. What is said of permanent winds ? What are these 
called by navigators ? 

4. Di >cribe the periodical winds. 

5. What are variable winds ? 

6. Describe the Hermattan. 

7. Where does the Sirocco blow ? What does it resem- 
ble r 

8. What is said of the Samiel ? 

9. What, of the Simoom ? 

Of Climates. 

1. What is a climate ? 

2. How many climates between the equator and polar 
circles ? — from each polar circle to its pole ? 



GRAMMAR OF ASTRGNGM1'. 17* 

Of the Aurora Borealis, Milky-icay^ cm£ Zodiacal Lights. 

1. What is the Aurora Borealis ? 

2. What i3 its general appearance ? 

3. To what cause is the Aurora Borealis attributed ? Is 
it ever seen in this country ? 

4. Where is the light of it the greatest ? What is the sup- 
posed extent of its streaks ? 

5. What is the Galaxy, or Milky-way ? 

6. Of what is it composed ? How many did Herschel enu- 
merate ? 

7. What is the Zodiacal light ? At what time does it 
appear ? What is its form ? 

Of Time. 

2. What is time ? and how is it divided ? 

2. What is a year ? How many kinds ? 

3. What is a tropical year ? 

4. What a sidereal or astral year ? 

5. What is the length of a common year ? 

6. What are the divisions of a common civil year ? 

7. What is a day ? and how divided ? 

8. What is a natural day ? 

9. What a civil dav ? How is it reckoned in the United 
States and in England ? 

10. What is an artificial day ? 

11. What, an astronomical day ? How reckoned ? 

12. What is a sidereal day ? 

33. What is an hour ? a minute ? a second P 

14. What is mean time ? 

15. What, apparent time ? 

16. What is equation of time ? 

Of the Globes. 

1. How many kinds of artificial globes ? 

2. Describe the terrestrial globe. 

3. What is the celestial globe intended to represent ? 
How is its motion ? 

4. Of what are globes composed ? 

5. What is the axis of the earth ? How represented ? 

6. What are the poles of the earth r What is called the 
north pole ? — the south pole ? 

7. How many circles are marked on the globe ? How d© 
the great circles divide it ? how, the small circles ? 

8. What are the small circles ? How is the tropic of Can- 
cer drawn? and how. the tropic of Capricorn ? Where is 



1JA GRAMMAR OF ASTRONOMY. 

the arctic circle ? and where, the antarctic ? What is the 
direction of these circles with respect to the equator ? 

9. What is observed of the circles of the sphere ? 

10. What is the horizon ? and how does it divide the 
globe ? 

11. How many circles are described on the face of the 
horizon ? How is the first marked ? the second ? The third 
contains what? the fourth, what? What does the fifth con- 
tain ? What, the sixth ? the seventh ? the eighth ? 

12. What is the brass meridian ? and how is it divided ? 
How does it divide the globe ? 

13. What is the equator ? and how does it divide the 
globe ? 

14. How is longitude marked? How is latitude reckoned? 

15. What is the ecliptic ? *• 

16. What angle does it form with the equator ? and what 
are the points of intersection called ? What are marked on 
the ecliptic ? 

17. What are the colures ? What are the equinoctial 
points ? and what, the solstitial ? What do these divisions 
mark ? 

18. What is the quadrant of altitude : 

19. What is the hour circle ? and what the index ? 

20. Parallels of latitude are what? 

21. What are circles of longitude ? What is the first 
meridian ? 

22. Describe the extent of the zodiac ? 

23. At what rate does the sun move through the zodiac ? 
W T hat signs are called northern signs ? what southern 
signs ? what is the greatest declination that the sun can 
ever have ? what, a star ? what, a planet? 

24. Describe the analemma. 



THE END. 



LIBRARY OF CONGRESS 




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